Aquaponics 9780992587864

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BY J O H N M A S O N & S TA F F O F AC S D I S TA N C E ED U C AT I O N

CONTENTS CREDITS

5

PREFACE

6

CHAPTER 1 SCOPE AND NATURE OF AQUAPONICS

7

What grows well in aquaponics?

9

Home systems

10

Commercial farms

11

Advantages of aquaponics

11

Aquaponics is about balance

12

CHAPTER 2 THE AQUAPONICS SYSTEM

13

What media is best for your grow beds?

18

What else do you need to consider?

21

CHAPTER 3 GROWING FISH IN AQUAPONICS

22

Key facts for growing fish in aquaponics

22

Feeding fish

25

How many fish?

26

Monitoring fish

26

Common problems and their symptoms

27

CHAPTER 4 FISH SUITED TO AQUAPONICS

28

Silver Perch (Bidyanus bidyanus)

28

Golden Perch (Macquaria ambigua)

28

Jade Perch (Scortum barcoo)

30

Murray Cod (Maccullochella peelii peelii)

30

Barramundi (Lates calcrifera)

31

Brown Trout (Salmo trutta)

32

Rainbow Trout (Oncorhynchus mykiss)

33

Carp 

34

Common Carp (Cyprinus carpio)

34

Catfish

34

Eel Tailed Catfish (Tandanus tandanus)

35

Channel Catfish (Ictalurus punctatus)

36

Silver Cobbler (Neoarius midgleyi)

36

Lake Argyle Catfish (syn. Arius midgleyi)

36

Eels (Anguilla)

36

Tilapia

37

Freshwater Crayfish

38

Marron (Cherax tenuimanus)

38

Red Claw (Cherax quadricarinatus)

38

Yabbies (Charax destructor)

39

CHAPTER 5 GROWING PLANTS IN AQUAPONICS

40

What system?

40

Planting guide

41

Planting

42

Herbs

43

Some herbs to grow hydroponically

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Basil (Sweet) (Ocimum basilicum)

44

Mint (Mentha spp.)

45

Parsley (Petroselinum crispum)

46

Vegetables

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Cabbage (Brassica oleraceae capitata Group)

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Lettuce (Lactuca sativa)

48

Pak-choi and Bok-choy (Brassica rapa ‑ pekinensis Group)

50

Spinach (Spinacia oleracea)

50

Other

52

Iris Species (Iris spp.)

52

Nutrients and deficiencies

54

Mobile and immobile nutrients

54

Plant nutrition

54

Nutrient deficiency

55

Control of water quality

57

Measuring pH and EC

57

EC Meters and EC Controllers

57

pH Controller

59

Plant pest and disease problems in aquaponics

59

Pests

59

Diseases

60

Damping-off disease

60

Grey mould

60

Powdery mildew

60

Wilt

61

APPENDIX

62

Distance learning and online courses

62

E-books by John Mason and ACS Staff

63

Printed books by John Mason

64

Useful contacts

65

ACS Global Partners

65

Social media

65

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CREDITS © Copyright: John Mason Written by Written by John Mason Dip.Hort.Sc. FIOH, FAIH, FPLA & Staff of ACS Distance Education Photos: John Mason Leonie Mason Layout Stephen Mason

The information in this book is derived from a broad cross section of resources (research, reference materials and personal experience) from the authors and editorial assistants in the academic department of ACS Distance Education. It is, to the best of our knowledge, composed as an accurate representation of what is accepted and appropriate information about the subject, at the time of publication.

P.O. Box 2092, Nerang MDC, Queensland, Australia, 4211 [email protected] www.acsbookshop.com

The authors fully recognise that knowledge is continually changing, and awareness in all areas of study is constantly evolving. As such, we encourage the reader to recognise that nothing they read should ever be considered to be set in stone. They should always strive to broaden their perspective and deepen their understanding of a subject, and before acting upon any information or advice, should always seek to confirm the currency of that information, and the appropriateness to the situation in which they find themselves.

P O Box 4171, Stourbridge, DY8 2WZ, United Kingdom [email protected] www.acsebooks.com

As such, the publisher and author do not accept any liability for actions taken by the reader based upon their reading of this book.

Editorial Assistants/Contributors: Adriana Fraser Barbara Seguel Gavin Cole Leonie Mason Published by ACS Distance Education

ISBN: 978-0-9925878-6-4

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PREFACE Aquaponics involves growing fish, crustaceans or something else in water; and then taking that water and using it to grow plants. It is an intensive way of producing food, that can be used on a small scale at home, or on a large scale for commercial farming. The level of sophistication involved in aquaponics can vary from low to high. The biggest challenge is to ensure that when the same water is used to grow two different things, the characteristics of the water needs to be compatible for both. The type of water required to grow some types of fish, for instance, can be quite different to the type of water needed to grow some types of plants. Success is achieved by both choosing plants and animals to grow that are compatible with the system you set up; and choosing a system that is compatible with the plants and animals you are growing. When you get these compatibilities aligned, you can then move forward, and provided that you manage the system appropriately, the potential for success can be staggering.

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Aquaponic farming allows individual families to grow a much wider range of produce, in a much smaller space. They can provide the protein needed for their diet (from fish), as well as the vegetables and fruit they need. Aquaponic systems can be as small as a few cubic meters; or as large as many acres. They are an ideal way of improving productivity on a hobby farm; can be used by restaurants to produce the freshest produce on site, or established inside buildings, in big cities, for urban farming. This book explores some of the more important considerations, and aims to inspire and inform you about the possibilities for aquaponics, in whatever circumstances you may consider using it.

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CHAPTER 1 SCOPE AND NATURE OF AQUAPONICS Aquaponics is a way of combining aquaculture or fish farming, with hydroponic growing. This is typically achieved by using the waste from fish tanks to fertilize plants, and waste water from plants to top up water in the fish tanks. The tricky part is to ensure that water taken from plants to fish, is chemically suitable for the fish, and that water taken from fish to plants is chemically appropriate for growing plants. The nutrient-rich waste from fish tanks can be valuable as plant food to vegetables and herbs grown in hydroponic beds. Chemicals (including nutrients) naturally increase in any water in which fish or other aquatic animals live. Some of these chemicals (such as

ammonia) are the result of excrement from the animals, and others may result from decomposition of dead animal tissue or left over food. As a result of its nutrient composition, water that is used for aquaculture is a useful source of nutrition for growing plants.

Golden Perch (Macquaria ambigua) is one of a number of freshwater fish species that have been grown successfully in aquaponics. PAGE 7

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In hydroponics you don’t use soil to grow plants - instead materials like gravel, perlite, river pebbles/stones, lava rock (e.g. pumice stones), clay pebbles  or rockwool may be used to anchor plants

Floating Gardens are the simplest form of aquaponics. Rafts are created to hold a growing media. Plants grow in the media. Provision must be made for water to either be absorbed through the bottom of the raft, up into the root zone; or for the root mass to penetrate through the bottom into the water. Example. A fly mesh bottom, and a media above that is mostly peat moss or sphagnum moss. Moisture will be absorbed up into the moss, keeping the roots wet.

In aquaculture fish is farmed under controlled or partly controlled conditions. Water quality needs to be carefully managed (e.g. faeces from fish might be filtered out and/or dissolved and passed through a tank or tanks where bacteria can convert any excessive ammonia to nitrites then nitrates, before applying the nitrate rich solution to the plant roots).

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into specifically designed, channel-like beds (usually raised at a convenient height). Water (with dissolved nutrients added) constantly reticulates through the beds.

Floating gardens of any size can be used in large ponds, dams or lakes; to grow certain types of plants. This photo illustrates a small one, growing “Impatiens”. Large floating gardens were established and used hundreds of years ago, by native people in Mexico; growing food crops on floating Islands. With fish in the water below, these were perhaps early examples of “aquaponics”.

Aquaponics can be used on a small scale or large and either commercially, or to grow food for your own use at home. Either way, both fish and plants benefit each other by creating a symbiotic relationship to produce a sustainable and integrated aquaponic system, which can yield produce all year long as long as it is in a suitably controlled environment.

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WHAT GROWS WELL IN AQUAPONICS? ■■ Plants such as leafy green

vegetables, vine plants, fruit and fruit trees, flowers, grasses and seaweed all grow well in aquaponics. 

■■ Freshwater fish and other aquatic

animals (e.g. crayfish) can be grown.

■■ The easier plants and animals to

grow will be the ones that are less sensitive to variations in water conditions (e.g. pH, nutrient levels).

Generally speaking, plants that don’t demand such high nutritional levels will survive and thrive best in most aquaponic systems. These include: common house plants; leafy crops such as kale, lettuce, pak choi; and herbs such as mint, basil, watercress, among many others. However, all others can grow strongly and vigorously too if the aquaponic system is well established and accurately monitored. It is advised that the variety of plants and fish you choose to grow meet similar pH and temperature standards in order to benefit from a more successful production.

An example of small scale hydroponics. If you add fish into the black tub that contains nutrient solution, this would become “aquaponics”. It becomes tricky though when choosing a compatible species of fish, and maintaining an appropriate level of plant nutrients in the water. Overcoming incompatibilities is the challenge of aquaponics.

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HOME SYSTEMS Although a relatively recent idea, home aquaponics is becoming increasingly realistic for the home garden.  Systems can be small enough to fit in even a small courtyard, or large enough to fill any amount of space you have available.   

as well as to provide a reasonable space for adequate plant growth and development.

Aquaponics systems are usually made up of grow beds (similar to a corrugated iron raised garden bed), a water pump, an air pump and a filtration system. You can now buy everything you need to get started; kits are readily available and these vary from very simple and inexpensive to quite complex and costly.  Before you jump in at the deep end and go for an expensive system it may be best to start small and then add on to the system as your experience and confidence increases. All types of aquaponics kits are now readily available online – try a quick Google search. If you like the idea of aquaponics but are not interested in eating the fish -  aquaponic grow beds for plants can be hooked up to existing ornamental fish ponds, as goldfish and other `nonedible’ fish species, work just as well as sources of organic plant nutrients, as edible species. A very basic aquaponic system simply composed of a fish tank, a filter bed or growbed (for the conversion of nutrients and wastes, as well as a growbed media, a stand, a water pump and a couple of PVC tubes and bell siphons assembled accordingly. The minimum area required to carry out this basic system should be of at least 1.5 square metres - this way it will be possible to move around the system PAGE 10

A simple aquaponics tank system.

A sturdy plastic fish tank should be placed partially underneath the stand, over which will rest the grow-bed container. The pump placed inside the fish tank provides two functions: - It firstly serves to aerate the water in the fish tank, along with the assembled PVC tubes and valves. -Secondly it carries the nutrient rich water from the fish tank into the growbed. A drainage system by another set of assembled and fitted PVC tubes and siphons will also be necessary for the recirculation of water from the filtering gravel grow bed setup (plants/ vegetables) back to the fish tank.

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COMMERCIAL FARMS Being very intensive - you may not need more than a few acres to contain a commercially profitable aquaponic farm. The costs associated with setting up and running an aquaponic farm can be significantly higher than other forms of farming though. Typically, you can save money on your land purchase, but what you save may then need to be invested in materials, equipment and construction.

Large scale hydroponic farm growing acres of lettuce; established by a former student of ACS Distance Education.

and, packaging etc.). Because you don’t need as much land, you can grow produce on more expensive properties, closer to larger population centres. ■■ It optimises the use of water

resources.

■■ Aquaponics is environmentally

friendly. Apart from growing your own food and fish, aquaponics can also help the environment - it conserves water (because we are recycling it and only topping up as the levels fall). This uses a lot less water than irrigation and, due to the constant recirculating water, there is a notable reduction in ‘water loss’ within each system. You are not using chemicals that can harm the environment and soil life, because you are using fish waste instead. Plants grow faster too and are not as susceptible to disease as soil grown plants.

■■ Many of the farming practices can

ADVANTAGES OF AQUAPONICS ■■ It optimises the use of land; it is an

intensive way to grow produce.

■■ You can grow more produce in a

smaller space than what is possible with conventional farming methods.

■■ It reduces food miles: ‘Food Miles’

is how far your food travels from paddock to plate - by reducing these ‘miles’ you can help save the environment (e.g. by reducing fuel usage, vehicles on our roads

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be automated, reducing labour costs and/or the use of large machinery.

■■ Being self-contained, it is not as

susceptible to variations in weather (e.g. drought, sudden temperature variations, if kept in a controlled climate environment such as a greenhouse or indoors).

■■ Greater control over production:

systems can be set up inside environmentally controlled buildings, water and air temperatures as well as light conditions can be controlled, and it is thus possible to create a farm that is productive all year round.

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■■ Systems that are enclosed in a

building and with environmental control have an ability to exclude contamination of animals and plants by pests and diseases that may impact on productivity.

■■ It is a more healthy and innovative

way to create organic produce.

AQUAPONICS IS ABOUT BALANCE In an aquaponics system you must grow a combination of fish and plants in separate tanks/beds. The ratio of fish and plants must be compatible to the size of the system, if you have too many fish you will overload the plants with too many nutrients. This can trigger lush growth that is susceptible to disease. Excess nutrients may then cycle back to the fish tank, and this can promote disease in the fish. Not enough fish means that your plants will starve and not do well. This makes them prone to insect attack, however a minimum amount of fish living in a tank will still allow a large amount of plants to thrive (it is important to find out which kind and ratio of fish/plants are most suitable for your type of system). Through careful monitoring though you can regulate and avoid nutrient overload, or under-load; it is all a question of balance. This is discussed in more detail later.

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The roots of a lettuce grown on a thin film of nutrient solution flowing along an NFT channel.

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CHAPTER 2 THE AQUAPONICS SYSTEM Aquaponic systems can vary greatly in size. They can be as small as an indoor fish tank or a large scale commercial aquaponics system. The type and size of aquaponics system you choose will affect the components and features that you will need to run it.

Expanded Clay balls, used as a hydroponic media to grow capsicum.

The hydroponic growing area may be either beds filled with a solid media or NFT Channels. The tanks or ponds that grow fish may be PAGE 13

large plastic or fibreglass tanks, or ponds made with concrete or liners. Earth ponds are probably inappropriate, because soil can contaminate and complicate efforts to maintain water quality.

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There are two types of systems - open or closed: ■■ Closed systems recirculate the

by commercial growers for example NFT (Nutrient Film Technique) or DWC (Deep Water Culture).

water – plants feed on a nutrient solution and the runoff then makes its way into ponds with fish (often being treated on its way). Water is then moved from the pond back to the plants. This system keeps reusing the same water.

■■ Open Systems do not reuse the

waste water.

An effective recirculation system needs to be able to treat the water in any way necessary so it can be used on plants; then take it from the plants and treat it appropriately in order for it to be used with fish. These treatments may involve removing organic wastes, neutralizing ammonia, removing pathogens, de-gassing carbon dioxide, oxygenating water, etc. A recirculation system offers the possibility of increasing stocking rates, decreasing growing times, improving productivity and profitability. It makes more efficient use of limited water resources. It also requires more costly infrastructure, and a more sophisticated operational management For the plant growing part of the system the most commonly used and effective system used in the backyard is media filled beds in a Closed Reciprocating System (CRS) - in single, two or three tiers, or even as a vertical system with plants growing on vertical grow beds rising above the fish tank . Other systems are available, but are complicated and more likely to be used PAGE 14

Example of a simple two tiered system.

There are several types of systems that are used in commercial aquaponics but the most common system for a backyard is the CRS, which also sometimes referred to as flood and drain cycles. Water flows through the gravel beds at intermittent times (controlled by a timer) to provide a more aerobic environment for the plants (i.e. providing greater access to oxygen) and prevent the chance of root waterlogging and rot. A typical Closed Reciprocating System has the following components: ■■ Tank (ponds or tanks) for growing

fish, crayfish or other species.

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■■ Hydroponic system for growing

For example:

■■ Collection tank or sump - lowest

The filtration system may include various mechanisms such as:

vegetables, fruits or other plants. point in a system that collects runoff from the hydroponics before pumping back into the aquaculture growing tank or pond.

■■ Filtration systems for removing

unwanted components in water.

■■ A biofilter to remove things like dead

animal tissues, uneaten fish food etc.

■■ A settling tank or compartment where

solids can be extracted from the water.

■■ A biofilter to convert toxic ammonia

in water to useable nitrates.

Example of a commonly used single tiered CRS system.

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Example of a vertical system.

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Three tiered systems are also popular as they save space and offer more growing space - here is an example of a typical three tiered system

Example of a three tiered system.

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WHAT MEDIA IS BEST FOR YOUR GROW BEDS? Choosing the best media for your growbeds is one of the most essential things to consider when starting up an aquaponic system as it is an important means for growth, aiding in the temperature balance and attachment of the roots of plants/vegetables. Growbed media also serves as a home for beneficial bacteria to develop, as well as a mechanical filter for solids and other wastes.

may ‘open doors’ to unwanted organisms to build up in your system. One commonly used media is scoria – it is cheap, readily available and does not affect the pH of the water.  Crushed local rock is another option but make sure that you avoid limestone or those known to be high in minerals as this will affect the pH and the possibility of nutrients locking up as a result. Expanded clay is a light, effective media but it is also quite expensive; it works great for plants with sensitive roots and its neutral pH will not alter the chemical composition of the water. Lava rock, such as pumice stone, is generally of low cost and also broadly used, however, its irregular shape might harm the roots of some plants. Also, as it is of volcanic origin, it is good to keep in mind that its chemical composition might bring unwanted impurities to the system.

Coarse sand, often used in hydroponic beds.

There are several options but for most types of media, particle size should be 8-16mm - no bigger or smaller. Smaller media doesn’t allow enough oxygen around the plant roots and could cause the system to clog as well as to prevent the water to flow freely through your growbed. Larger media is very difficult to plant your plants into. It is important to find out which growbed media may decompose throughout the time as this PAGE 18

Scoria, a red volcanic rock, can be suitable for hydroponics, if it is available locally.

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Example of an aquaponics CRS system using gravel beds.

Hint: Once you have your system in place, run it for a few days before introducing fish – that way you can check for leaks, test to make sure the water is right for your fish, or make any changes if they are needed before you start introducing fish or plants. Hint: In order for ammonia wastes from fish (not useful to plants in this form) to convert into nitrates (that can be used by plants as nutrients), you need beneficial bacteria in the water of your aquaponics system. This is called nutrient cycling. If you have access to an aquarium filter (used) or some fish-pond or aquarium water then put a bucket of this into your tank to get the system started. Another way to get bacteria started is to throw some fish feed into the tank and let it sit for a few days before introducing the fish – bacteria will start to feed on the ammonia it produces and to multiply in the system.  Bacteria will establish of their own accord of course, but it takes a bit longer. PAGE 19

A simple system with vegetables in a tray above, draining into a tank below.

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Pumps that are not submersible come in all shapes and sizes. Some are suitable for aquaponics, and others may not be. Consult an expert on pumps who also understands aquaponics if you want to avoid potential problems.

Tanks that are designed for water storage or other purposes are often used for growing fish in an aquaponic system. Be sure that they are clean though and do not contain anything that may impact the water quality or fish health.

A submersible pump under the water is used to move water out of this old bathtub as fresh water splashes back into the tub from the hose on the right. PAGE 20

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Concrete tanks, ponds or even disused swimming pools can be suitable for aquaponics, provided they are clean and do not contaminate the fish. Remember, fresh concrete can leach out chemicals; and swimming pools that have used salt or chlorine for a long time, may have residues of chemicals in places as well.

WHAT ELSE DO YOU NEED TO CONSIDER? ■■ You need at least 6 hours of

sunshine for your plants to grow well.

■■ Fish do not need sunlight – sunlight

on tanks encourages algae (locating your growing beds over the fish tanks can help eliminate this) or grow floating plants on your fish tank.

■■ You will need access to power for

your water and air pumps.

■■ You will need easy access to

harvest your plants – don’t make beds too wide and make sure you have access from all sides.

■■ You will need easy access to tend to

your fish and to harvest them.

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■■ Make sure that your tanks are not

contaminated with leaf drop from nearby trees – it makes it harder to keep them clean.

■■ Make sure that your children or pets

cannot fall into the fish tanks.  Fish tanks should be covered with mesh to stop birds and cats preying on fish.

■■ If fish require treatment with salt

water or other medications they should be removed from the system for this purpose as plants do not grow well in saline conditions and if any treatments used for fish health should be kept out of the growing system too (i.e. put the fish into a separate ‘quarantine’ bucket/tank as long as required).

Hint: Solar water heaters are a very effective and cheap way to heat the fish tanks.

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CHAPTER 3 GROWING FISH IN AQUAPONICS

By keeping aquaponic tanks under cover, it is easier to manage water quality and temperature. Too much light can cause algal blooms, too much rain can change the water chemistry, and extreme weather can increase or decrease water temperatures to levels that impact on the animals in the tanks.

KEY FACTS FOR GROWING FISH IN AQUAPONICS ■■ Different fish species have

different requirements: some tolerate impurities or lower levels of oxygen in the water than others, while some survive best within a specific temperature range; but as a rule, you will have faster growing, healthier fish, when you manage the water more carefully, irrespective of what type of fish you are growing.

■■ Generally, don’t mix species of fish

in the same tank. Choose something that suits your needs then manage conditions for that species.

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■■ Your choice of fish should depend

upon both what your system is suited to, and what you want to harvest. If growing fish for your own use, you may consider what you like to eat. If growing to sell, you may consider what is going to be easiest to sell (e.g. what is in demand at the time), and what will bring the best price.

■■ Low oxygen level in the water is a

common way that fish are killed in aquaponics. Pumps must continue running to keep oxygen levels up. There are many reasons why pumps may not run for a period; and provision needs to be made to manage and avoid any situation where the pump stops (e.g. power failures, disconnecting a pump for repair, unplugging a pump). You may consider having a battery or petrol powered pump as a back-up.

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■■ Over feeding fish is another

relatively common way fish are made sick or killed. Any food that is not eaten by fish within 3-5 minutes should be removed. Uneaten food decomposes in water, causing an increase in ammonia which can poison fish.

■■ pH levels need to be stable. Many

fish species can adjust to gradual changes in water pH, but may be killed by fast changes.

■■ Water temperature should not

change rapidly. Some fish species will tolerate higher or lower temperatures than others, but most do not respond well to quick changes.

■■ Don’t put too many fish in a body

of water. Overstocking makes it far more difficult to maintain water quality and control disease.

■■ Smaller tanks are more prone to

variable conditions; and as such this makes it easier to grow fish in larger volumes of water. If you start with a small system, keep it in a place where temperatures are more stable (e.g. a veranda or inside a shed, out of the sun), and understock the tank rather than overstocking, so you have better control over water quality.

■■ Aquatic animals commonly grow

better when the water contains higher levels of oxygen (i.e. DO or Dissolved Oxygen). Colder water can hold more oxygen than warmer water however water temperature can also be a factor in growing fish or crustaceans. Warm water animal species have often evolved to cope better with lower levels of dissolved oxygen. Water can only hold a certain amount of oxygen though, and animals living in the water are constantly removing and lowering oxygen levels. This makes it critical for you to continually replace the oxygen that is being removed. You do this by aerating the water. Dropping water into a tank from a return pipe can help and bubbling air from an outlet at the bottom of a tank can also. 

■■ Ammonia build up in water can be

Fountains, cascades or water wheels are a simple way to increase oxygen levels in water; but can also increase or reduce water temperature faster in extreme weather.

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a problem, particularly in warmer water. Levels of 1ppm are dangerous. Any level of total ammonia above 0.5ppm can be considered dangerous for many species. Different species can have different levels of susceptibility. Bacteria in the water do convert ammonia into nitrate which feeds algae; but there needs to be a balance in this cycle so ammonia doesn’t build.

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■■ Productivity is affected by stocking

rated. Overstocking can reduce growth rates.

■■ Water hardness is a factor that can

affect the ability to grow animals. Hardness may have originally been a term used to refer to how well soap lathers up in water which is essentially related to the concentration of calcium and magnesium. In aquaculture it refers to the total concentration calcium carbonate in terms of parts per million (ppm).  Soft water is 0-55ppm. Hard water is 200 to 500ppm. Calcium is needed for bones of fish and the shells of crayfish. Some types of animals need it more than others and as

such, some animals need harder water than others.  Fresh and saltwater crayfish, for instance, tend to need hard water at a higher ppm. ■■ The water pH required for growing

plants needs to have a level of compatibility with the pH require for growing fish (or other aquaculture) – around pH 6.8 - 7.2 is ideal for fish and most plants will tolerate that range too.  Keep in mind that the water pH may also be changed by the system as it goes from hydroponics to aquaculture or aquaculture to hydroponics. Some types of growing bed media may also affect the pH in the recirculating water.

If water is allowed to drop through the air when it returns to a pond or tank, it will oxygenate the water; but if the return pipe is below the water surface, there will be no significant increase in dissolved oxygen.

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Feeding Fish Fish generally need a high protein food. Fish may well gain a certain amount of food from algae and organisms that occur naturally in the ponds, but supplementary feeding is the norm as well. When growers will produce their own supplementary food, they have the advantage of controlling impurities. What they produce on their own property is more likely to be clean: free of diseases or pollutants that might be introduced unwittingly in food they buy in from outside the property. Proprietary fish rations produced by reputable manufacturers for aquaria and commercial aquaculture should normally be safe, and such products are normally properly formulated and well balanced foods with the correct nutrients for healthy fish growth. They are also an added cost though. Always feed the fish as much as they can eat in 3-5 minutes, at a considerable proportion, and then remove the excess so it prevents ammonia levels from accumulating too much (from decaying food on the bottom of the tank) – remember decaying food also consumes oxygen needed by your fish! Chose the pellets to suit the type of fish species you are growing because protein requirements for healthy growth changes according to the species; carnivorous species such as bass, perch or trout (for example) need higher protein levels than omnivorous species (e.g. carp (koi), tilapia, silver perch). Making your own fish food pellets: make them out of a combination of animal PAGE 25

protein, plant protein and grains. The danger is if you don’t get your formulation right, you will cause an increase in levels of ammonia. So, apart from considering the protein content ratio your fish should be eating, it is also important to differentiate these ratios with the stage of maturity your fish is in, as well as their ‘seasonal diet’ (some fish require different nutritional values at certain times of the year, so it is helpful to find out the natural feeding cycle of the fish you are farming as if it was in the wild). A great advantage of making your own fish food pellets is that you have total control of what your fish eat, which, in turn, can considerably lower your overhead costs as opposed as if you were to be buying commercially manufactured pellets. Foods that you might consider growing are: Some people also like to give their fish alternative feeds such as worms, maggots and saw fly larvae but use the pellets as a base for their feed. ■■ Black Soldier Fly larvae (Maggots)

- High quality food, will grow in food scraps from the kitchen; will crawl out of the compost up a ramp (if provided) and drop into a container of water when ready to harvest as a fish food - you can then collect from the water and then feed the fish.

■■ Duckweed - High quality fish

food (dry weight can be up to 40% protein), has an added advantage in that it will reduce ammonia levels in water and it grows fast - can double its mass every 1 to 2 days.

■■ Snails - Crunch and drop into tank.

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■■ Earthworms - Very important part

of an aquaponic system if the final goal is to feed your fish a varied diet. However, although worms have plenty of protein content, they are also high in fat, which many fish would not specifically require (the age of the fish is also important to consider, for instance, in some species, juveniles will require more fat/protein content for growth and development than a more mature fish).

■■ Mosquito larvae - They may be

found around the tanks.

How Many Fish? Like the amount of plants you can harvest, the amount of fish you need also depends on quite a number of factors including: ■■ How often they are fed. ■■ The water flow. ■■ The oxygen levels. ■■ The pumping rates ■■ And also the number of plants you

want to grow.

You can grow quite an amazing array of plant produce with relatively few fish. For example: for every 250 litres of (25cm deep) bed media you use - you need about 10 fish. And in a 500litre tank you can very easily grow about 10 fish - in this system you can expect to harvest good sized table fish. Remember: If you want more grow beds then you will need more tanks and more fish. PAGE 26

Bubbling air through a tank or pond will oxygenate the water. Fish may be attracted to where the bubbles rise because oxygen levels are higher in the water at that point.

MONITORING FISH In order to grow healthy, disease free fish the following all need to be within appropriate levels. Many aquaponics kits will also come provided with testing kits, so you can effectively monitor these issues. If not then buy yourself a test kit that tests pH, ammonia, nitrite and nitrate is best. ■■ Water temperature and quality -

Temperature is vital to the survival of fish. Temperature fluctuations outside of the normal range for fish species can induce shock in fish and possibly lead to death. The climate of your region will influence the heating and cooling you will need. Water quality is also important and water sources need to be tested. Tap water for example will need to be de-chlorinated, tank water too can be problematic especially if the materials they are constructed of are leaching toxic chemicals. Bore water has a high pH and this will also need

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to be adjusted. When adding new water to the system you should do so in small quantities to allow the fish to adjust. ■■ pH - Measure of how acidic or basic

(alkaline) the water is. The pH level is usually higher at the beginning of a cycle and then gradually decreases once a system has cycled completely. In general the pH should be between 6.8 and 7.2 – but tolerances can vary slightly outside of that.

■■ Dissolved oxygen - Dissolved oxygen

is required by all fish to survive. The water properties and stocking densities will affect its ability to hold oxygen. For example, warmer water will hold less oxygen. As discussed earlier, in order for fish to survive, the water must be aerated.

■■ Ammonia - This is the first product

of the nitrogen cycle. There are two forms of ammonia. Unionized ammonia is most toxic to fish. 

■■ Nitrite - This is the second product

of the nitrogen cycle. Nitrite is produced by the oxidation of ammonia by bacteria and is highly toxic. An increase in ammonia concentrates will be detrimental to fish health. Remove excess feed to prevent this. This problem can be avoided by installing a plumbing off-take from the main pump line. This ensures good water circulation by feeding into the top of the fish tank. Circulating water keeps the food particles floating and these can then be more easily removed by the pump and filtered back into the grow beds. Adding more fresh water and reducing the pH also limits problems with ammonia excess.

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Note: Some people install a settling tank or swirl separator to remove the larger particles of solids from their tanks, such as fish manure and uneaten food, so that there is not an over load of ammonia or nitrites. This is not totally necessary though as long as you monitor your system carefully; some people think that removing the solids removes fertility from your plants. Algae – tanks in sunlight can experience problems with algal growth – this is detrimental to health of your fish, the bacteria in your tank or the plants you are growing; place your tank out of sunlight to avoid algae.

Common Problems and Their Symptoms Fungal Infections Symptoms: often show as white blotches on the skin and fins. Remedy: you can minimise this problem by adding potassium carbonate to your system, or chose resistant fish species such as Silver Perch.

Ammonia Toxicity Symptoms: loss of appetite, fish gasp, red inflamed gills plus red blotches on skin and fins. Remedy: filtration, dilution with fresh water, pH management, settling tank.

Low Dissolved Oxygen  Symptom: fish die overnight, gasping fish – more prevalent in warm temperatures and in the presence of algae. Remedy: aerate the tank more effectively.

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CHAPTER 4 FISH SUITED TO AQUAPONICS Silver Perch (Bidyanus bidyanus) Australian native fish

■■ Relatively easy to grow; fast

growing.

■■ Used widely in Australian

aquaponics - adapts well to recirculation systems.

■■ Needs a medium protein diet: Eats

duckweed, pellets and yabbies.

■■ Tolerates higher temperatures than

■■ Fingerlings can grow to between

400 and 600gm in one year.

■■ Murdoch University developed an

effective closed system treating water from a silver perch tank, with a biofilter to convert ammonia to nitrate; then recirculating into NFT channels using the nitrates to feed plants.

■■ Some have been known to reach as

much as 6kg.

■■ Subtle taste to eat, but flavour can

vary, it can carry through the flavour of the pond in the fat in the flesh.

trout (ideal 22 to 28°C).

■■ Does not tolerate above 35°C., won’t

feed below 10°C.

■■ Requires a water pH of 6.5 to 8. ■■ Water hardness 50 to 200ppm. ■■ Can be sensitive to noise and light. ■■ Breeding is induced with HCG

(human chorionic gonadotropin). Once eggs hatch young feed on zooplankton and algae; then are weaned onto artificial feeds.

■■ Can be bought as fingerlings in

Australia (Narrandera Fisheries Research Station in NSW, began a hatchery in the 1970’s).

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Golden Perch (Macquaria ambigua) Also called Yellow Belly

■■ Farmed in both dams and

recirculating systems.

■■ Water temperature 15 to 25°C. ■■ pH 6.5 to 8. ■■ Water hardness 50 to 200 ppm. ■■ They tolerate a broad salinity range,

however, the higher the salinity levels, the less chances of spawning to occur.

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■■ Carnivore preferring live food; which

can make feeding difficult. Needs a high protein diet. Main food sources include yabbies, shrimp, insect larvae and other fish

■■ Particularly hardy in captive

environments.

■■ Not as aggressive as Murray cod or

Barramundi.

■■ Needs clear water. ■■ During their breeding period, tanks

Golden Perch

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should be kept dark. Eggs take between 1-2 days to hatch. ■■ Larger ponds tend to be needed. ■■ Their common weight is around

4-8kg but can weigh up to 20kg in captive environments.

■■ Good demand for this fish in

particular in Jewish and Asian communities.

■■ Fast growth rate, reaching up to 500

gr in 18 months.

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Jade Perch (Scortum barcoo)

■■ Water hardness 50-200 ppm. ■■ Needs a medium protein diet. ■■ Can grow to 500gm in one year.

■■ Needs warm water: tropics or sub

tropics (20 to 30°C). It won’t feed at temperatures below 15°C.

■■ Water pH 6.5 to 8.

■■ Farmed in re-circulating systems

and static ponds.

■■ Generally not as profitable as

Golden or Silver Perch.

Murray Cod

Murray Cod (Maccullochella peelii peelii)

■■  Can be aggressive and territorial,

■■ Provide lots of different hiding

places to cater to territorial nature, so each fish can create its own territory.

■■ Needs a high protein diet.

making management difficult in smaller tanks.

■■ Do not take to feeding with pellets

■■ Water temperature ideally between

■■ Has been farmed in re-circulation

■■ pH 6.5 to 8.

■■ Existing market may be limited, but

15 and 25°C.

■■ Water hardness 50 to 200ppm.

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as readily as perch. systems.

potential is good.

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Barramundi (Lates calcrifera) Also known as Asian Sea Bass

■■ Will grow in either fresh or salt

water; Barramundi breed in saltwater, young fish are males and move inland to fresh water, as they grow they turn into females and swim downstream toward the sea. Their adaptability to salt and fresh water makes them very useful in aquaculture and aquaponics.

■■ Adult fish can grow as large as

almost a metre.

■■ Farmed in dams and tanks. ■■ Aggressive nature. ■■ Requires high temperature 25 to

30°C. (Optimum 28°C). Avoid below 22°C.

Barramundi

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■■ Water pH 7 to 8.5 is optimum. ■■ Water hardness 50 to 100ppm

(Some authorities suggest to 400ppm).

■■ Water filtration is important. ■■ Needs high protein food. ■■ If fish bioload is high, ensure plant

bioload is also high.

■■ Growth rate depends partly on feeding.

A 2 to 1 growth rate is possible (i.e. eating 2kg of food can increase the body weight by up to 1 kg.

■■ Well suited for aquaponics provided

water quality, food and water temperature are appropriate.

■■ Commercial supply is relatively well

catered for, particularly for smaller (plate size) fish. There is a greater market for larger fillet size fish (around 3kg at harvest, which takes about 18 months to grow).

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Brown Trout (Salmo trutta)

■■ Do not tolerate above 26°C. ■■ Feeding is as for Rainbow Trout. ■■ Main commercial value (in Australia

and some other places) is as an angling fish.

■■ Not as hardy as some other trout

species.

■■ Needs good aeration.

■■ You may consider growing for your

Brown trout, gutted and ready for sale or freezing.

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own use; but harvesting and selling as a food may be limited.

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Rainbow Trout (Oncorhynchus mykiss) ■■ One of the hardier species of

salmonoids.

■■ Tolerates higher water temperatures

than some trout (ideally 10 to 22°C).

■■ pH 6.5 to 8. ■■ Water hardness 50 to 200ppm. ■■ Grows in fresh or salt water. ■■ Farmed commercially but

normally in flow through systems (open systems).

Rainbow Trout

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■■ Feed should be high in protein.

Trout do not digest carbohydrates well, but they do digest fats. They are sometimes fed fish offal and slaughterhouse by products. Alternatively they may be fed pellets.

■■ Dried feeds reportedly increase

growth and productivity. Commercial feeds prepared specifically for trout are available in some countries.

■■ The type of feed can affect the

taste.

■■ Feed 3 or 4 times daily. Feed fry

more often.

■■ Profitability is not high - easy to

grow but no more so than salmon, which can bring a far higher price per kg. Can grow 500gm in 18 months.

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Carp  Common Carp (Cyprinus carpio) is the most widely grown of many species of carp. ■■ Carp is a pest in some places

(banned in some states in Australia); but globally, it is perhaps the most widely farmed type of fish.

■■ Very hardy and adapts to a diverse

variety of water conditions.

■■ They survive over a cold European

winter so long as the pond is deep and there is not too much organic material on the bottom of the pond (decomposing organic matter takes oxygen from the water which is detrimental to fish.

■■ Common carp will breed all year

round if water is kept warm. Ideal hatching temperature is 20 to 25°C (Indian and Chinese carp like slightly higher temperatures). Eggs hatch in about 3 - 5 days.

■■ Have been used as a food fish for a

long time in both Europe and Asia. Popularity as an eating fish has been in decline in Europe.

■■ Used commercially as a fish based

fertilizer for plants.

■■ Common carps are considered to

be benthivores (they feed off bottom sediments). Some food sources include microcrustacens, mollusks and plant matter when adults, and

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macroinvertebrates, benthic insects and detritus when juveniles. ■■ Can survive large temperature

ranges: between 3°C - 35°C, however, their optimum growth temperature is best between 23°C 32°C.

■■ Optimum pH levels: 7.0 – 7.5,

however they can still survive if pH levels reach as low as 6.5 and as high as 9.0.

■■ Can tolerate oxygen levels as low as

0.5mg/l up to saturation.

■■ Average length is from 25 - 35cm. ■■ The can commonly reach 3 – 5 kg in

weight.

■■ They can live more than 20 years

if adequate living conditions are present.

Catfish There are over 1200 different species, most are freshwater animals some are saltwater. ■■ Many species are scale-less; all

have feelers around the mouth.

■■ Farmed in aquaculture a lot in the

USA.

■■ Many species have a tasty white,

sweet flesh.

■■ Low fillet recovery per kg is a

restrictive factor in commercial potential.

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■■ Many are very hardy, and can be

rapidly growing. Some (e.g. Bullhead

Catfish) are considered a pest.

There are over 1,200 different species of catfish; some of which are important in aquaculture and well suited to aquaponics. ■■ Average length varies between 50

Eel Tailed Catfish (Tandanus tandanus)

and 90 cm.

■■ Their life span can be up to 8 years,

if kept in a healthy environment.

Native fish in the warmer parts of the Murray Darling basin in Australia; also found in the smaller lakes of NorthWestern Victoria and Western NSW. ■■ A bottom dweller, often fed with

sinking pellets, however, they will reach the surface for food is it available (e.g. flakes).

■■ Carnivores. Main sources of food

include molluscs, yabbies and shrimps. Will also eat worms, insect larvae, snails, and even frogs and toads.

■■ Can weigh approximately between

1.5 and 6.8 kg.

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■■ Optimum range of temperature is

between 17°C - 23°C +2°C.

■■ Desired pH levels should remain

between 6.5 and 7.5.

■■ Often found solitary in the wild, so

communal tanks are not advisable. One or two per tank is preferable but if it is a reasonably large tank, Murray Cod, Silver Perch and Golden Perch are suitable. Avoid keeping them with smaller fish.

■■ They tend to reproduce in the

warmer seasons (between late spring and early summer months). If breeding is in mind, it is recommended to provide a

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gravel bed for them, as they tend to build their nests from this material. Protect the eggs from predators (including other fish) – eggs should hatch in approximately 7 days. ■■ Males and females can be

distinguished by their protuberance behind their vent: males have a long and round-shaped papilla, while females have a triangleshaped papilla.

■■ White and firm flesh and no scales.

It is said to have a delicious and delicate flavour.

■■ Beware of their spines when

handling! And do not try to approach them during their nesting period; they will feel threatened and will attempt to attack.

■■ While most catfish aquaculture

has been in large ponds or dams, some has been successful in large rectangular or round tanks; which can be incorporated into an aquaponics system.

Silver Cobbler (Neoarius midgleyi) Also known as:

Lake Argyle Catfish (syn. Arius midgleyi) Popular with anglers in northern Western Australia.

Eels Channel Catfish

(Anguilla)

(Ictalurus punctatus)

Several other species of Ictalurus are also farmed in the USA. ■■ Fry are reared in a trough or pond at

24 to 29°C, with dissolved oxygen a minimum of 6 ppm.

■■ Fingerlings are then transferred to

larger ponds.

■■ Water should be around 29 °C, pH

6.3 to 7.5 and dissolved oxygen levels around 4 to 5 ppm.

■■ An indication of low oxygen levels is

fish coming to the surface gulping air.

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Have been farmed successfully in freshwater re-circulating systems in Europe ■■ Young eels are susceptible to many

different diseases, but as they age, resistance becomes much stronger.

■■ Grow in water pH 6.5 to 8, and at

least 15°C (but ideally 20 to 23°C).

■■ Young eels (called “Elvers”), 5cm

or longer, are caught in the wild, for growing in aquaculture.

■■ Eels are cannibalistic on smaller

animals hence need to be sorted according to size.

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■■ Young eels can try to leave pods or

tanks, particularly in rainy weather, so sides need to be vertical with water level well below the rim to prevent then getting out.

■■ Eels can be harvested in Japan at

100 to 120gm after one year, but more commonly they are grown to 200gm, taking up to 2 years.

■■ Popular in European and

Asian markets.

Tilapia species from Mozambique ■■ Have been grown successfully in the

Tilapia

same water as other fish including channel catfish, mullet and carp.

■■ Different species have different

Popular for aquaculture in many parts of the world, but banned in some places (e.g. considered a noxious pest in Australia). There are many species, From Africa, and the middle east; farmed commercially in some countries, including the USA, India, Philippines and Taiwan. Three of the more important species for aquaculture are Tilapia aurea, Tilapa mossambica and Tilapia nilotica.

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optimum requirements (e.g. temperature, food, stocking density, salinity tolerance, etc.), so it is important to select the right species for the situation at hand.

■■ A potential problem can be

overstocking. If fish spawn in a grow-out pond or tank; this can result in too many fish and stunted growth. This problem is sometimes controlled by introducing predatory animals such as catfish or eels that will feed on the young fry.

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Freshwater Crayfish

Predators can be a major problem. Netting is often hung above ponds to prevent birds taking animals. Stress is another big influence on production. If you can minimize stress to animals, your productivity is likely to be far higher.

Marron (Cherax tenuimanus)

A freshwater crayfish from south west Western Australia. ■■ Can be relatively slow growing but

eventually reaching around 1kg.

■■ Has been farmed successfully in re-

circulating systems; and may have potential for aquaponics

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Red Claw (Cherax quadricarinatus) A freshwater crayfish from northern tropical Australia. ■■ Does not tolerate low winter

temperatures.

■■ Fast growing at high densities. ■■ Normally grown in dams or pods,

but may be able to be adapted to aquaponics.

■■ Tolerates warmer water

temperatures than Marron.

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Yabbies (Charax destructor) An Australian freshwater crayfish, hardier than Marron and Red Claw. ■■ They can survive in poorer quality

water than some other aquatic animals, but for good production, you need good water quality.

■■ They are detrivores (eating

microbes rotting vegetable matter in the water).

■■ They also feed on phytoplankton

(algae) and small animals (e.g. insect larvae and worms).

■■ Grows across a wide range of

climates.

■■ In the wild, females carrying

fertilized eggs appear in late winter.

■■ Breeding may be triggered by

increasing day lengths combined with improving temperature and food supply.

■■ Optimum water temperature is 22

to 26°C.

PAGE 39

■■ Feeding depend on water

temperature. In cold water, during winter, feeding may be rare, but when water temperatures are good feeding can be as often as two or three times daily.

■■ Grows mostly in static ponds

and dams; but may be able to be adapted to aquaponics.

■■ pH levels between 6 and 9 are

acceptable. The optimum pH is 7 to 8.5.

■■ Can get to 350gm, but commonly

not more than 150gm.

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CHAPTER 5 GROWING PLANTS IN AQUAPONICS The plants you choose to grow need to be compatible with the aquaponic system you are using.

Water returning to fish tanks at a commercial farm.

WHAT SYSTEM? There are lots of possibilities - here are just some: ■■ Nutrient Film Technique (NFT):

water, which includes nutrients, flows constantly (film) over the plant’s root system – this is usually done through a channel or series of channels such as PVC pipe or guttering. Plants may be held in perorated/net pots (baskets) containing growing medium (e.g. scoria, pebbles, clay pellets etc.),

PAGE 40

that are inserted into holes along the top of the pipe. This is normally a “closed” system, with a constant flow of nutrient solution. The solution flows through the channel, providing water and air to the plant roots; and is collected in a tank at the bottom of the channel, from where it is pumped back to the top. This type of system has been used satisfactorily for aquaponics - but it is critical that you choose compatible species of fish and plants, when there is a constant flow of water like this.

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■■ Gravel Bed Culture: a tray or bed is

filled with a mixture of aggregate, which plants are planted into. The bed is irrigated with a nutrient solution periodically (perhaps once daily), and excess solution is drained off into a sump or pond. If the water is appropriate for aquaculture, you might grow something in that pond; but if it isn’t appropriate, you may treat that water first, before passing it onto another pond, for aquaculture.

■■ Ebb and Flow: plants in containers

(e.g. perforated/net pots) filled with aggregate or rock wool cubes) are placed into a tray. The tray is situated above a tank or pond that holds water and nutrients which is pumped to the tray at intervals using a timer. The tray fills with the nutrient rich water, as the timer switches in, and then drains the solution back through a filter, or via another tank, into the aquaculture tank.

Herbs and leafy vegetables are the most commonly grown edible plants in aquaponics. They grow faster and produce more leafy material than the same plants grown in soil. There is less stress, especially in the hotter weather, as plants have constant access to moisture; this also encourages fast and lush growth. Many leafy vegetables and herbs are ready within 5 weeks of planting. A range of other plants have been successfully grown in hydroponics including cut flowers such as roses, carnations and chrysanthemums, and berry plants such as strawberries and raspberries are also commonly grown in aquaponics.

■■ Capillary Systems: nutrient solution

is supplied to some sort of absorbent material below the plants. It soaks into the material and is absorbed upwards to the root zone. This way the roots (in theory) never get too wet or too dry.

PLANTING GUIDE What can you grow in aquaponics? Almost any vegetables can be grown successfully in aquaponics - and although root vegetables do pose problems it is possible (with adaptions) to also grow potatoes in aquaponics. Sweet potatoes on the other hand do very well. Strawberries growing in an NFT system PAGE 41

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Here is a list of plants that may be appropriate: Basil Beans Beetroot Belgian endive Broccoli Bok Choy Cabbage Cauliflower Capsicum Carnation Celery Chervil Chilli

Chinese cabbage Chrysanthemum Cucumber Coriander Dill Eggplants Ginger Impatiens Iris Kale Lettuce Parsley Peas

The Easiest Plants Some of the easiest crop plants to consider for aquaponics may be plants that thrive in wet conditions, such as cut flower Iris, water chestnuts, water cress.

PLANTING The aquaponics system is constantly producing nutrients so because of this you need to make sure that your grow beds always have plants in them – accordingly plants will be at various stages of development i.e. seedlings, half grown and full grown plants should be in your grow bed at all times. As you harvest or remove mature plants you should immediately replace them with seedlings. ■■ Wash the soil off the roots of

seedlings before planting so you don’t contaminate your grow beds with fertiliser, potting soil and sand. Just wash off the soil in a bucket of water.

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Pumpkins Rose Rocket Salad onions – red or white Silverbeet Snow Peas Spinach Spring onions/shallots Sweet potatoes Tomatoes Water cress Zucchini

■■ To prevent transplant shock add

some sea weed emulsion (e.g. Seasol) to the bucket of water, hold the seedling gently by the leaves and swish the roots around in the water

■■ Again holding the seedlings by its

leaves move aside some of the growing media in the planting beds and insert the seedling – then gently push the media back around the roots system.

■■ Some people also scatter seeds

onto the grow beds rather than plant seedlings – the scattered seeds fall between the growing medium and germinate in situ. Smaller seeds (e.g. lettuce, spinach, silverbeet etc.) seem to work better than larger seeds. You can pre-germinate larger seeds (e.g. beans, peas, cucumbers, pumpkins etc.) on tissues or paper towels placed in ziplock bags and then transplant the germinated seeds into the grow beds once they have sprouted a 25mm or so root. This

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also allows you to better position these larger seeds (as they produce larger plants). ■■ Plant quite densely – a lot closer

together than you would in a vegetable garden bed i.e. about twice as close. However you must make sure that there is still enough air circulation around your plants to prevent fungal problems.

■■ When plantings climbing beans, peas,

cucumbers etc. plant the seedlings at the edges of the tank and insert a climbing frame before planting – you may need to encourage your plants onto the frame.

HINTS: ■■ Keep plants away from the auto-

siphon in your system – roots grow strongly and can clog up the system in a matter of days.

■■ Use a greenhouse to extend your

growing season.

■■ Make sure your grow bed/s is in a

sunny position – however in summer you may need to cover your vegetable beds with 20 - 40% shade cloth.

■■ Plant pumpkins on the edge of the

bed; pumpkins can easily overwhelm a bed so keep a close eye on it and encourage the plant to spill over the bed and downwards onto the ground where it can ramble at will.

■■ Check all purchased seedlings for

insects (and remove) before planting – never plant obviously diseased, stunted or otherwise unhealthy seedlings.

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HERBS The only herbs that do not seem to thrive in hydroponics are woody herbs such as rosemary, savory and thyme. Rosemary is grown hydroponically though, but it may not live as long or produce as well as it would in the ground, so if you want to grow it you are best to choose a variety that produces lots of flat prostrate new growth such as Rosmarinus ‘Huntington Carpet’. This is also the case for thyme, it will grow hydroponically, but you may not get a very big harvest; rhizomes such as ginger and bulbs such as garlic are best avoided – but most other herbs will thrive. Some herbs will grow better than others if nutrition is variable, provided they are kept moist (e.g. mint). The pH is the acidity or alkalinity of a solution or growing most herbs is best at neutral or below. The optimum pH for most herbs is between pH5.8 – 6.5. Most fish however do not like the pH below 6.5 but will cope best with a range of pH 6.8 – 7.2, which is within the tolerance range of most plants; to achieve the best pH for both fish and herbs requires keeping the water within a relatively narrow pH range. Controlling the pH is important for healthy plant growth – if the pH is wrong then the plant will show signs of nutrient deficiency; nutrients become available to plants (i.e. able to be absorb through the roots system), at certain pH levels and become unavailable if the pH is wrong. In hydroponics systems pH is usually regulated through the addition of buffers e.g. phosphoric or nitric acid (in dilute

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amounts) to lower the pH and potassium hydroxide to raise pH. In aquaponics you can also add buffers to regulate your pH but pH regulation can be quite difficult to maintain – this is discussed in more detail later this chapter. HINT: when you set up your system you will need to buy a pH water test kit or an electronic pH monitor. It is important that you test the pH daily but always at the same time of the day because pH does tend to fluctuate during daylight hours when photosynthesis is at its greatest. pH will rise then drop again once the plants start to respire at dusk. HINT: for hard water (with a high pH) an alternative is to buy a RO filter (Reverse Osmosis) – this works to filter out all impurities from the system including carbonates which raise pH.

SOME HERBS TO GROW HYDROPONICALLY Basil (Sweet) Ocimum basilicum

A kitchen must! Basil grows well in hydroponics producing lush and tasty leaves.

Growing Conditions: ■■ Temperatures of 20-24°C are ideal

and a pH range of 5.5 – 6.5

■■ Needs continually moist but well

aerated root environment

PAGE 44

■■ Needs good light conditions,

although some shade may be needed in summer

■■ The ideal media is scoria or pebbles

and they do well in NFT, media beds or DWC (Deep Water Culture) systems

■■ Requires good nitrogen uptake – so

watch out for nutrient depletion in the water.

Planting Seed germinates in 4 to 7 day at 21°C; plant out in clay-balls, rocks or pebbles once the seedlings have 4-5 sets of true leaves at 15 – 25cm spacing in early spring in warm areas early summer in cooler regions. Trellis support may be needed.

Harvest Start harvesting before flowering starts this also prolongs the life of the plant – just pinch out new growth often. The plant will continue to send out new growth (and flowers) until about mid-autumn when the plant should be removed.

Problems: ■■ Vigorous roots can clog NFT

channels after a while.

■■ Whitefly ■■ Planting too early – in cooler

climates this can cause plants to sit and sulk rather than grow; it also makes them more prone to insect attack. Early December is the best planting time in cooler areas.

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Mint (Mentha spp.) There are several species of mint available for culinary purposes (usually Mentha x piperita or Mentha x spicata or forms thereof – some have a coarser taste than others. Those with lighter green leaves are tasty and strong – darker leaves are hairier and coarser. It all does depend on your taste too. You may need to try before you buy!

Growing Conditions:

■■ Aphis and mites can also be a

problem.

■■ Vigorous root system can block

NFT channels or block your filter system. Plants should be replaced periodically.

Harvest: ■■ Like basil pinched out growing tips

(use in the kitchen) as this keeps young growth occurring.

■■ Mint is usually dormant in winter re-

emerging in spring.

■■ Mint likes wet conditions and

medium aeration around the roots system. It grows best in milder temperatures (15°C to 20°C). NFT has been very successful for mint.

■■ pH 5.5 to 6.0 – this is quite low for

the fish in aquaponics, but it will tolerate a slightly higher pH.

Planting: Plant cuttings or divisions in late winter – wash any soil or media off the roots system thoroughly, especially if you are using divisions, but also for cutting grown plants.

Problems: ■■ The main problem with mint is

rust – it is almost unavoidable and although difficult to control if you cut back the first growth showing signs of rust right back to media level the new growth which appears a bit later in the season tends to be rust free.

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Mint is a herb that can thrive in wet conditions; and that characteristic may be an advantage for using it in aquaponics.

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Parsley (Petroselinum crispum) Parsley is another stalwart in the kitchen – versatile and nutritious so well worth trying aquaponically.

VEGETABLES Leafy vegetables have been relatively successful for growing in aquaponics.

Cabbage (Brassica oleraceae ‑ Capitata Group)

Growing Conditions: ■■ Parsley is tolerant of cold

temperatures.

■■ It needs good aeration, but constant

moisture in the root zone and does exceptionally well in aquaponics.

■■ Parsley does not do well in NFT as

roots can tend to rot - so media bed culture (scoria or pebbles) is best.

■■ pH 5.5 – 6.0

Planting: Space seedlings at 10 to 20cm intervals for optimal growth.

Problems: Few pest and disease problems but some insects can mark foliage occasionally.

Harvest and Post-Harvest: You can start harvesting parsley once they are well branched this can take about 10 weeks from planting. Parsley is a biennial plant which means it flowers and seeds in its 2nd year. It is best to grow it as an annual in a hydroponic system. PAGE 46

Growing Conditions: ■■ Aeration should be very high ■■ Constant moisture is important ■■ Ideally temperatures above 13°C

should be maintained at all times – ideal temperature being 15 - 20°C.

Nutrient Requirements: ■■ High levels of nitrogen, phosphorus

and potassium are particularly important, plus iron.

■■ Has a higher than average boron

requirement

■■ Ideal pH is 6.2 to 7.2.

Suitable Growing Methods: ■■ Gives excellent results from

aggregate culture.

■■ Not suited to newly established

aquaponics units – allow 4 months before planting into a new system.

■■ 20% shading with shade cloth in the

warmer months to prevent bolting.

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Planting: ■■ Smaller varieties can be sown at a

distance of 30cm x 30cm between plants once they have 6 or so true leaves.

■■ Larger varieties will need to be

spaced 45cm x 45cm apart.

Problems: ■■ Cabbage white butterfly grubs must

be controlled. Exclusion fabric is very suitable in aquaponics (to exclude the moths).

■■ Other pests can include aphids,

flea beetles and maggots – careful monitoring is required to prevent infestation.

■■ Cabbage can be attacked by several

fungi including fusarium, downy mildew, and alternaria leaf spot.

Harvest and Post-Harvest: Harvested cabbages can be stored for a month or more after harvest at 0 to 3°C and low relative humidity.

Varieties: There are varieties available to crop at all times of the year.

Cabbages and other brassicas are vegetables that grow better at a higher pH than most other vegetables; a factor that may make them more compatible with aquaculture.

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Planting:

Lettuce (Lactuca sativa) Growing Conditions: ■■ Growth needs to be fast and at an

even rate (will mature in 40–85 days depending on variety).

■■ Shading may be needed in hot

conditions. Some varieties (e.g. leafy types) are slower bolting, reacting more slowly to higher temperatures. These are most suited to growing in warmer months.

■■ The root zone should never over-

heat making aquaponics an ideal growing method.

■■ Most varieties prefer temperatures

between 12 and 22°C.

■■ Temperatures over 27°C can affect

quality and cause flower stalk development.

Nutrient Requirements: ■■ Lettuces require moderate nutrient

requirements too strong or too weak can lead to irregular growth.

■■ Ideal pH is 6.0 to 7.0.

Suitable Systems: ■■ Vertical columns, Media bed, NFT

or DWC. Modified NFT with gravel in gullies is also very successful.

■■ Coarse aggregate culture gives excellent

results in any medium 10cm deep.

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Germinate seed in vermiculite, perlite or rockwool propagation blocks, then transplant into system at 6 to 8 leaf stage. Sow direct into aggregate beds then thin out.

Special Cultural Techniques: Remove marked or damaged outer leaves.

Problems: ■■ Irregular bursts of growth can cause

decreased quality or quantity of produce.

■■ Rapidly-grown lettuces are relatively

free of disease.

■■ Excess water or poor aeration

commonly causes yellow or rotting of the lower (outer) leaves.

■■ Some will burn on the leaf tips if

exposed to too much sunlight – light shade cloth can prevent this.

■■ Pests include aphids, flea beetles,

crickets, springtails, leaf hoppers, caterpillars, whitefly, slugs and snails.

■■ Aphids are of particular concern

because they transmit viral diseases.

Other disease problems include damping off (pythium), sclerotinia, downy mildew, powdery mildew, botrytis, rhizoctinia, and anthracnose.

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Harvest and Post-Harvest:

■■ Lettuces are ready to pick after four

weeks in summer.

Salad Greens growing in NFT.

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Pak-choi and Bok-choy (Brassica rapa ‑ Pekinensis Group) Growing Conditions: ■■ Requires a lot of moisture, but also

reasonable drainage.

■■ Growth ceases at temperatures

below 10°C.

Nutrient Requirements: ■■ Ideal pH is 7.0 ■■ Otherwise similar nutrition and

conditions to cabbage.

Suitable Growing Methods: As for Cabbage.

Planting: ■■ Can suffer transplant shock. ■■ It is preferable to germinate in its

permanent position.

Problems: As for cabbage.

Harvest and Post-Harvest: Harvest 70 to 80 days after planting.

Spinach (Spinacia oleracea) Growing Conditions: ■■ Plants prefer cool, shaded positions. ■■ Plants thrive best in temperatures

between 15 and 19°C.

Nutrient Requirements: ■■ Nitrogen is most important. ■■ Plants are sensitive to a lack of

manganese, copper, molybdenum and iron.

■■ Ideal pH is 6.0 to 7.0.

Suitable Systems: ■■ Most aggregate media at 10cm deep

will give excellent results.

■■ Also NFT pipes and DWC.

Planting: ■■ Sow seed in sand or perlite and

transplant into the aquaponic system at the 6–8 leaf stage.

■■ Space plants 8-10 cm apart.

Problems: Chewing insects, slugs and snails can be a problem.

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Suitable systems

Water Chestnut (Eleocharis dulcis)

Aggregate; DWC.

Planting Growing conditions: Chinese Water Chestnut grows as a semi-submerged plant and so is highly suitable for aquaponic production.

Nutrient requirements: Nutrient requirements may be fairly small.

Small corms are planted in spring. Loose media is appropriate for Water Chestnuts

Harvest and post-harvest Large corms are harvested after leaves die off in autumn. Corms will reach about 50 mm in diameter.

Where space is limited, the hydroponic component of your system can be a vertical garden like this. PAGE 51

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OTHER

Problems: ■■ Overwatering will cause bulb or

Iris species (Iris spp.) Growing conditions: In high humidity, plant rhizomes or bulbs close to the surface of the media. In hot dry air conditions, plant deeper (2-5 cm below the surface).

Nutrient requirements: Little specific information available.

Suitable systems: Depends on the type of iris; some types require very little aeration and will grow completely submerged in water, others do not. Iris laevigata needs to be in extremely wet conditions to thrive. It would be best suited to (DWC) deep water culture. Iris germanica requires a very well aerated situation. Dutch, Spanish and English irises generally like a drier, better-drained medium than average. These would be best tried in gravel or scoria beds.

Planting: Plant bulbs or rhizomes direct into the media.

Special cultural techniques: Some support system is necessary.

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rhizome rot.

■■ Pest and disease problems include

snails and slugs, aphis, thrip, bulb flies, viral diseases, leaf spot, ink spot and iris ruts.

■■ Frost can be a problem with some

types.

Harvest: Cut when flower begins to appear in the flower.

Varieties: Irises are classified as follows: Bulbous types: ■■ Xiphiums (Dutch, Spanish, English)

- these are popular as cut flowers worldwide.

■■ Early flowering and small

Reticulatas.

■■ Junos varieties.

Rhizome types: ■■ Bearded - have fleshy rhizomes

and large wide bladed leaves. These generally prefer warm, dry conditions.

■■ Beardless have narrower leaves

and smaller fibrous rhizomes. These prefer wet situations.

■■ Crested – have thin rhizomes.

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Irises can be grown as valuable cut flowers, even in submerged planters as shown here, with fish in the same pond.

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NUTRIENTS AND DEFICIENCIES Plant nutrient deficiencies are common in the first 6 months of setting up your system (it takes time for the bio-filter to fully establish) – to overcome nutrient problems it is common to add a liquid seaweed emulsion (this is quite safe, as long as toxic chemicals have not been added, as may be the case with some seaweed based fertilisers).

MOBILE AND IMMOBILE NUTRIENTS Nutrients are known as mobile or immobile depending on the nutrient. Deficiency symptoms related to mobile nutrients occur in the older leaves first because mobile nutrients move from older leaves to newer leaves in order to assist health and growth. Deficiency symptoms related to immobile nutrients occur in newer leaves first because (being immobile) these nutrients do not move from older leaves to newer leaves - they are fixed so cannot assist the health and development of newer leaves. Mobile nutrients include: nitrogen, phosphorus, magnesium, potassium, chloride, molybdenum. Immobile nutrients include: Iron, calcium, copper, zinc, sulphur, manganese, and boron.

PLANT NUTRITION Plants require different nutrients in different quantities; the quantity of nutrient required by a plant will vary from one plant to another and from time to time throughout different stages of its growth. Plants will usually display definite deficiencies if required nutrients are not present in adequate concentrations. The following symptoms (see table below) may occur if the level of one mineral nutrient is not high enough to be within the range needed for best plant growth. A plant may exhibit a particular symptom for reasons other than a nutrient deficiency. However, if one of the deficiency symptoms occurs, a lack of the proper nutrient may be suspected. Some nutrient elements are needed by the plant in very large quantities while others are only needed in very small quantities. Those used in large quantities are called major (macro) elements; ones needed in small quantities are called minor elements. Macro and minor elements are both just as important to healthy plant growth despite the differences in the quantities which the plant uses. Nitrogen, phosphorus, potassium, sulphur, iron, calcium, magnesium, manganese and boron are all major nutrient, Plants can grow with limited nutrients; however this will affect their appearance and flavour. They may also be more susceptible to disease without adequate nutrients. For low nutrient requiring plants such as leafy vegetables and salad greens,

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nutrient deficiencies are usually not a problem once the aquaponic system is mature, however heavy feeding crops such as tomatoes often need additional calcium, potassium and iron for good yields and fruit quality. 

the pH is incorrect).  And remember that you must think about the fish as well as the plants when altering pH levels. Note: Plants that are either underfed or overfed are prone to disease and insect attack. For every 80 grams of fish food (added each day) you can grow approximately 1 square metre of plants.

NUTRIENT DEFICIENCY The general yellowing of leaves is known as chlorosis and this is a common problem in aquaponics. 

Trout fingerlings being raised for sale to be used in aquaculture or aquaponics.

Adding Nutrients Where the pH in the system is falling, potassium and calcium hydroxide can be added as they will help maintain a stable pH level.  Where the pH is higher, potassium sulphate is a useful source of potassium.  Iron can be supplemented with iron chelate, the best type being Fe-DTPA which is most suited to the pH levels aquaponic systems typically run at. Remember to always check the pH before adding any nutrients - in aquaponics pH is more likely to be the problem behind nutrient deficiency (i.e. plants are unable to uptake nutrients because they are not accessible when PAGE 55

When the veins remain green but leaves yellow between the veins – this is termed as interveinal chlorosis and often a symptom of an iron deficiency. Iron deficiency is common in aquaponics because it isn’t adequately present in fish food. Iron chelates can be added to the water if the pH is right for your fish (over pH7) but plants are showing signs of chlorosis (iron is locked-up in a high pH and then it is not available to your plants). If you need to add iron chelates (available in liquid form) – the usual dosage is 2mg per litre of water (but check the product you buy and follow the instructions) every 3 weeks. To test your water for iron deficiency you can also buy a testing device – that way you can pre-empt the symptoms before they appear in your plants. The target range for iron in the water should be between 2-3 parts per million (ppm), and anything below 1.5ppm will show up as chlorosis in the leaves of your plants.

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DEFICIENT NUTRIENT

SYMPTOM

Nitrogen

Leaves are small and light green; lower leaves lighter than upper ones; not much leaf drop; weak stalks.  Nitrogen toxicity can also occur in aquaponics – this is where the plant is getting too much nitrogen – symptoms include dark green leaves that eventually turn black and fall off the plant.

Phosphorus

Dark-green foliage; lower leaves sometimes yellow between veins; purplish colour on leaves or petioles.

Potassium

Lower leaves may be mottled; dead areas near tips and margins of leaves; yellowing at leaf margins continuing toward centre.

Calcium

Tip of the shoot dies; tips of young leaves die; tips of leaves are hooked-shaped.

Magnesium

Lower leaves are yellow between veins (veins remain green); leaf margins may curl up or down or leaves may pucker; leaves die in later stages.

Sulphur

Tip of the shoot stays alive; light green upper leaves; leaf veins lighter than surrounding areas.

Iron

Tip of the shoot stays alive; new upper leaves turn yellow between veins (large veins remain green); edges and tips of leaves may die

Manganese

Tip of the shoot stays alive; new upper leaves have dead spots over surface; leaf may appear netted because of small veins remaining green.

Boron

Tip of the shoot dies; stems and petioles are brittle. 

Note: Many of these nutrients may be supplied to plants via food fed to your fish, after bacteria have converted chemicals for plant use. Fish food can be a useful plant plant fertiliser.

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CONTROL OF WATER QUALITY It is possible to monitor and control water characteristics automatically, but to do so can become complex and costly. For a commercial operation it may be very worthwhile. For a small scale amateur aquaponic system, it may be more viable to just avoid the more difficult species of plants and animals. One key thing is critical though – any changes that occur should occur gradually (eg. sudden changes in pH can cause shock and kill fish, but the same change made gradually, may be tolerated.) As fish and plants are constantly taking chemicals from the water to use, they are also leaving other components or unused chemicals behind. The concentration of what is removed is decreasing, and at the same time, the concentration of what is left behind is increasing. Recapping on previous chapters - there are three things that are of particular concern i.e. residual components will over time: 1. Change the pH (acidity). 2. Increase the concentration of unwanted salts 3. Cause a build-up of ammonia. As discussed earlier ammonia can be converted to less toxic nitrite by bacteria, but this is a process that can take time (about 6 weeks in fresh water). Some types of growing media will encourage PAGE 57

the growth of these “ammonia converting” bacteria (e.g. scoria or expanded clay are both excellent for promoting this good bacteria). If ammonia levels do increase too much, it is possible to lower them quickly by using zeolites (a type of rock dust). If you place zeolites in water for no more than 12 hours, the zeolites will extract ammonia; but if left longer than 12 hours, the ammonia can start to leach back into the water (hence remove after 11 or 12 hours).

MEASURING PH AND EC The pH can be measured with a pH meter – they are not too expensive and a tool that is mandatory for successful aquaponics. The total salts concentration can be determined by measuring electrical conductivity (EC) of the water in your aquaponic tanks). Electro conductivity needs to be monitored closely as the nutrient concentration will be continually dropping due to nutrients being taken out and used by the plants growing in the system.

EC Meters and EC Controllers An EC meter (Electrical Conductivity meter) is a device which measures the flow of electricity between to electrodes. If the concentration of salts in the solution is stronger, there will be a stronger flow of electrons. An EC meter

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won’t tell you the type of nutrients in your water just the total EC.

should be undertaken every two weeks.

There is much and varied information and advice on the use or effectiveness of EC meters in aquaponics however they can be a useful tool for measuring total EC. A salinity controller monitors and shows the EC level in the solution at all times, and operates injection pumps which add concentrated nutrient solution to the solution in the system when the level falls. EC will increase if temperature increases. Because of this, it is necessary to provide temperature compensation in the salinity control system. This is usually calculated on the basis of 2% per degree centigrade. A salinity controller automatically compensates for EC drop bringing it back to a predetermined level, thus maintaining optimum nutrient levels at all times. Over a period of time, there can be a build-up of unused salts (i.e. nutrients which are not used). This can create an inappropriate EC reading which will make adjustments to the setting on your salinity controller necessary. Alternatively the solution needs to be replaced with a fresh solution. Although salinity controllers can maintain nutrient solutions for periods at optimum levels, it is advisable chemical analysis of the nutrient solution (for nitrogen, potassium, calcium, magnesium, phosphorus and iron) also be carried out from time to time. In large commercial operations, such a chemical analysis PAGE 58

Electoconductivity (E.C.) meter

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pH Controller A pH controller is a device linked to an electrode in the catchment tank. The electrode measures the pH of the nutrient solution and relays the reading to the controller. The controller can be programmed to inject predetermined amounts of acidic or alkaline solution into the catchment tank if the pH reaches an upper or lower limit. This way, the pH of the solution can be brought back to a level which is suitable for the plants being grown. White vinegar is often used to reduce pH in aquaponics, and bicarbonate of soda to increase pH. If the pH drops below 6.0, there are likely to be serious problems with many types of fish; and below 5.0 can cause corrosion in parts in the pump. In pure hydroponics (no fish) nitric or phosphoric acid are used to correct high pH in nutrient solutions; but in an aquaponic system you must also consider how any additives might affect any fish you are growing. They are pre mixed in 1:10 or 1:20 with water and injected into the catchment tank as required, allowing maximum mixing to occur before the adjusted solution is delivered to the plants. When mixing concentrated acids: always add the acid to the water. It can be very dangerous adding the water to the acid.

PLANT PEST AND DISEASE PROBLEMS IN AQUAPONICS PESTS Slugs, snails, aphids, white fly and thrips are all common pest problems in aquaponics, white cabbage moth is also a pest of members of the cabbage family: ■■ Use organic methods so as to

not affect the fish in the system - handpick caterpillars or use a product such as DiPel (Bacillus thuringiensis, a natural soil borne bacteria), or use IPM (integrated pest management) and introduce natural predators such as ladybugs and lacewings (can be sourced online).

■■ Use potassium bicarbonate as a

spray for fungal problems.

■■ Wash off aphids etc. with the hose. ■■ Set sticky yellow traps for aphids,

whiteflies and thrips.

■■ Check for snails and slugs daily and

set saucers of beer to attract them (they die in the beer).

■■ Use exclusion fabric over your beds

to prevent white cabbage moth.

Note: Only some organic methods are acceptable in aquaponics (as above), others will harm the fish. In particular organic soap/oil sprays for pest control should not be used in aquaponics as they are toxic to fish. PAGE 59

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DISEASES The most common disease problem in aquaponics is fungal disease – lack of air circulation is usually the culprit; make sure your plants have good air circulation. If symptoms are severe you may need to remove your plants, sterilise the growing medium and start again. There is little control you can use without affecting the health of your fish.

Damping-Off Disease This is common in humid environments – newly emerged seedlings rot off at the base.  This disease is caused by various species of spore producing pythium. Cause:

Botrytis cinerea. Lesions appear in the first instance on the leaves and stems. Cause: ■■ High humidity ■■ Lack of airflow ■■ Contaminated tanks

Remedy: Improve ventilation.  ■■ Practice good hygiene; clean out tanks

and sterilise the growing medium.

■■ Remove affected plants, do not

compost them. 

■■ Contaminated sediment tanks

Powdery Mildew 

■■ Insufficient light

White spots appear on the leaves followed by brown lesions and white powdery growth caused mainly by Leveillula taurica or Oidium neolycopersici. 

■■ Insufficient ventilation ■■ High humidity

Remedy: ■■ More light ■■ Improve ventilation ■■ Clean out tanks  ■■ Sterilise growing medium

Cause: ■■ Lack of ventilation ■■ Humidity ■■ Contamination

Remedy: Carefully monitor air flow and humidity.

Grey Mould

■■ Remove and destroy affected plants

This is very common in aquaponics and hydroponics especially when grown in a greenhouse and is caused by the fungus

■■ Sterilise growing medium and clean

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– do not compost. out tanks.

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Wilt This disease is common in both aquaponics and hydroponics. The older growth is affected first and the disease then spreads to younger leaves; the plants wilt and eventually die. Plants are also often stunted and chlorotic. The fungi Verticillium dahliae or Fusarium oxysporum are usually the culprits. Cause: Lack of ventilation ■■ Humidity too high ■■ Infection from contaminated tanks

Remedy: Improve ventilation and humidity – clean out tanks sterilise growing medium.

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APPENDIX DISTANCE LEARNING AND ONLINE COURSES The authors of this book have developed a large variety of distance learning courses, (online, on CD or by correspondence), which are available through various colleges that are part of the ACS Global Partners Network. There are over 600 different courses offered by ACS Affiliates, through colleges across seven different countries. Short courses are generally 100 hours in duration. A range of qualifications such as certificates and diplomas are also available. These courses cover a wide range of disciplines, including Business, Management, Marketing, I.T., Biological Sciences, Health, Fitness, Nutrition, Psychology, Counselling, Writing, Photography, Hospitality, Tourism, Education, Construction, Horticulture, Agriculture, Environmental Management and more. See www.acs.edu.au/about-us/affiliates.aspx

Courses that may particularly helpful to readers of this book include: ■■ Home Hydroponics

■■ Marine Studies

■■ Aquaponics

■■ Water Gardening

■■ Hydroponic Supply &

■■ Irrigation

Consultancy

■■ Hydroponics I, II & III ■■ Certificate in Hydroponics ■■ Aquarium Management ■■ Aquaculture (Freshwater) ■■ Mariculture

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■■ Horticulture ■■ Vegetable Production ■■ Permaculture ■■ Farm Management

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E-BOOKS BY JOHN MASON AND ACS STAFF INCLUDE: Starting a Business

Starting a Nursery or Herb Farm

Project Management

Aerobic Fitness 2nd edition

Business Operations

Aquafitness 2nd edition

Psychology Dictionary

Nutritional Therapy

Counselling Handbook

Human Nutrition

How Children Think

Animal Health

Farm Management 2nd edition

Horse Care

Profitable Farming 2nd edition

Dogs –Caring for Dogs

Working in Horticulture

Marine Animals

Commercial Hydroponics 3rd edition

Professional Writing

Trees and Shrubs for Warm Places

English Grammar

Organic Gardening

Getting Work in a Modern World

Climbing Plants

What to Plant Where

Growing Conifers 2nd edition

Psychological Profiling

Roses

Getting Work in Horticulture

Herbs

Scented Plants

Trees and Shrubs

Modern Marketing

What to Plant Where

Poultry

Fruit, Vegetables and Herbs

Growing Ferns

Growing Tropical Plants 2nd edition

Human Biology Dictionary

The Environment of Play 2nd edition

Leadership

Garden Design Part I

Palms

Garden Design Part II

Creative Writing

Tropical Landscaping

Weeds

Starting a Garden or Landscape Business 2nd edition

Medical Terminology

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Food Preserving

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PRINTED BOOKS BY JOHN MASON John Mason has been writing books since the 1970’s and has over 40 titles published, some as printed books, others as ebooks. Some titles are out of print, and now only available as secondhand books or e books. If you have difficulty finding any of Mr Mason’s titles, you can enquire by email to [email protected] Print Books by John Mason include: Fun and Fitness Trails, Victorian Dept. of Sport and Recreation, 1978 Starting a Nursery or Herb Farm, Night Owl, 1983 (revised 1994) The Environment of Play, Leisure Press, New York, 1982 Herb Review, self published, 1987 Landscaping with Herbs, self-published, 1988 The Native Plant Expert, self-published, 1989 Let’s Grow Gardens, self-published, 1990 Growing Ferns, Kangaroo Press, 1990 Commercial Hydroponics, Kangaroo Press, 1990, 2007 Growing Vegetables, Kangaroo Press, 1991 Growing Herbs, Kangaroo Press, 1993 Nursery Management, Kangaroo Press, April, 1994 Tropical Gardening, Bay Books, October, 1994 Yates Guide to Pests & Diseases, Angus & Robertson, February, 1995 Growing Pelargoniums & Geraniums, Hyland House, 1996 Farm Management, Kangaroo Press, 1996 Growing Australian Natives, Kangaroo Press, 1997 Starting a Nursery or Herb Farm (Revised ed), Kangaroo Press, 1997 Sustainable Farming, Simon & Schuster (Kangaroo Press) Spring, 1997 Growing Tropical Plants, Simon & Schuster (Kangaroo Press), 1997 Starting a Landscape or Garden Business, Kangaroo Press, 1998 Aqua Fitness, Kangaroo Press, 1999 Growing Conifers, Kangaroo Press, 1999 Profitable Farming, Kangaroo Press, 1999 A Beginners Guide to Orchids, Hyland House Aerobic Fitness, Kangaroo Press Trees & Shrubs for Small Places, Kangaroo/Simon & Schuster, 2000 Propagating from Cuttings, Kangaroo/Simon & Schuster, 2002 Growing and Using Vegetables and Herbs, Kangaroo/Simon & Schuster, 2007

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USEFUL CONTACTS ACS GLOBAL PARTNERS To see the latest list of ACS affiliates, please visit: www.acs.edu.au/about-us/affiliates. aspx

SOCIAL MEDIA Stay in touch with the authors through our various social media: FACEBOOK AUSTRALIA CLICK HERE 〉〉 FACEBOOK UK CLICK HERE 〉〉 TWITTER CLICK HERE 〉〉 LINKED IN CLICK HERE 〉〉

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