Sep 14

Famine And Aquaponics

Drought has struck again in the African Sahel.  Most of these people are nomadic herdsmen and there is no grass or forage left. War in Mali has sent millions of refugees pouring over the border into Niger, where conditions are no better.

They have, as far as I know, no aquaponics.

Aquaponics is an organic food factory that produces up to four times more food than conventional soil agriculture, using 90% less land and WATER than conventional agriculture in the process.  This is revolutionary.

No expensive chemical fertilizers or pesticides are needed or can be used.  Not only do you get vegetables and soft fruit such as melons out of an aquaponic system farm, but also tonnages of TILAPIA FISH to solve the famine problem.  Using far less water than conventional farming.

So you can provide the refugees with food, stop the famine, and also, after a little basic on-site tilapia fish aquaculture and horticulture training, jobs and skills to take them further in life.

Famine, given this aquaponics technology, can be eradicated quite quickly.  Green leafy vegetables such as lettuce and cabbage varieties come out of an aquaponics system as harvest only 8 weeks after switching it on, and continue to be harvested weekly thereafter, as long as the aquaponics system is correctly managed and maintained.

This is only intermediate technology and can be run of alternative energy systems such as concentrated solar power and anaerobic digesters.

The tilapia fish and vegetables all are in tanks, in a closed-circuit recirculating aquaculture system.  This system can be built and set into motion within eight weeks of the equipment and stock ( tilapia fish fingerlings and seeds) arriving on site.

Only a half horsepower pump and two regenerating blowers (air pumps for water aeration) are needed to service 0.05 of a hectare of aquaponics system.  This produces 5 metric tonnes of tilapia fish and weekly continous harvests of vegetables in quantity.

These units can be built using simple materials like concrete and plastic water piping.

Here at Aquaponics Global we are available as consultants on contract to mitigate famine and food security emergencies using aquaponics technology anywhere on the planet, for reasonable fees.  We are all multilingual expatriates with years of experience of coping with unusual and stressful conditions and have the requisite qualifications and experience to be rapidly effective in problem-solving on the spot in our various disciplines of aquaponics, aquaculture, construction (architecture), and business administration.

If you are a logistics professional looking for rapid ways of slowing or halting famine situations in drought areas without needing vast inputs of fertilizer, water, and expensive genetically altered organisms, Aquaponics Global can help.  Why not give us a call?

Call me! - Charlotte Appleton: Offline

» Get Skype, call free!

Jul 16

Water Gardening With Aquaponics.

Aquaponics is growing fish and plants in the same integrated recirculating water aquaponics system.  This is usually used commercially to grow up to twice as much food in up to half the time normally needed in conventional agriculture.  That is up to four times as much food as on the same space used by conventional agriculture.

Also, a lot of edible fish are needed to be farmed in the system, as well as the crops, in order to nourish the plants.

koi carp

Koi carp.

But you can also grow a lot of ORNAMENTALfish, such as koi carp, quite intensively in your aquaponics system.  Not as intensively as tilapia, which are more robust, but at quite a high fish stocking ratio, as long as you have enough plants growing in your system to eat up the nitrates produced in the filtration media. Some varieties of tilapia and trout are also very pretty to look at. Blue Australian marron crayfish are fascinating and bright blue! Water gardening is also for the aquarist. Gardening here also means looking after commercially farmed fish if you like.

water garden

water garden

You can of course grow ornamental plants in an aquaponics system. But did you know that there are a lot of vegetable plants that are also ornamental and that grow fast in an aquaponics system? They make water gardening with aquaponics very easy.

Okra, for instance, is a form of hibiscus.  It has a spectacular flower. It goes crazy in a floating raft aquaponics system.

okra flower

Flowering okra

There are lots of varieties of green vegetables which are also ornamental, such as fancy lettuces which come in all sorts of colours from green through to purple and almost black, and with different forms of frilly leaf shapes. Artichokes, if left to flower, are a giant thistle.

Lots of culinary herbs such as basil also come in different leaf colours and/or have attractive flowers. They also have fascinating scents.

And a lot of other plants which are not generally eaten such as marigolds and many varieties of plants used for cut flowers will also grow in an aquaponic system.

By constructing hydroponic beds to resemble the many different levels of a flowing stream, with waterfalls which also help to maintain water aeration, you can put together a very attractive aquaponic water garden with recirculating water going back to the ornamental tanks full of fish.

This recycling of the water with your water gardening means you will safely only use around 10% or less of the water used by conventional gardeners, as long as the tanks remain mostly covered with floating rafts or floating vegetation. You can even water garden in a hose ban or drought with aquaponics!

lettuce colors

Some colors of lettuce

If you liked this article, I have collected similar articles about aquaponics in the more than 30 chapters of ‘Aquaponics Global Anthology 1′ printable ebook, available for download here: [paiddownloads id=”1″]

Jun 15

Aquaponics – Your Community Food Bank


By getting together with other members of your local community to exploit unused spaces such as back lots and rooftops, along with waste heat and water from buildings and also food waste from restaurants and institutions, you can build integrated aquaponics systems into your area that will serve as a permanent food bank in these hard times.

You must have seen the film clips in which desperate people sit on street corners with notices saying “Will work for food.” Well, with a community aquaponic farm in place on one or several sites, people can work for food and also for other things like valuable experience and social networking on the farm.  When your farm is finished and in full production, excess food can be sold to pay a living wage to the stalwart workers who have helped to make it all happen. You may find that the farm very rapidly outperfoms expectations as a local food bank.

Building an aquaponic system can either be a million-dollar large commercial enterprise made of state of the art technology, or it can be just as sophisticated, but built out of recycled materials garnered from skips and building sites, and friendly donations of bags of concrete and rolls of LDPE pond liner.  You will need to build tanks and these can be cobbled together successfully in a variety of ways. Aquaponics is always a stimulating design challenge, but with so many successful systems like the University of the Virgin Islands type aquaponics system already proven to work, it is better to follow their lead rather than reinventing the wheel!

If you are going to use wood in aquaponics system tank construction, you should make sure it is sound and thoroughly termite and rot proofed before it is incorporated into any tank structure.  Also be very careful about copper sulphate compounds that are routinely used for rot proofing wood.  These are lethal to fish and plants.  So any such treated wood must be painted over with a non toxic paint as well to make sure the water in the system is not contaminated with copper!  If you can, use steel pipes and galvanized heavy duty welded fence wire in tank construction rather than wood for your aquaponics system. That way you avoid your tanks rotting and breaking before you can harvest the fish inside. Wood can break your food bank!

Do not use any copper pipes or implements when doing aquaponic farming.  Copper pipes and wires may be all right inside your house, but copper is a fish farmer’s and hydroponic farmer’s nemesis. Avoid it at all costs.

Fish are very sensitive to any heavy metals and will die if their water is in continuous contact with any of them (copper, lead, silver, rusty iron, and so on). When building your aquaponic food bank, remember this is not at all just book learning. You are working with living, breathing creatures who have minds of their own.  Fish and plant wrangling can be stresssful since a food bank of this sort is also a living species bank!

Various means can be used for heating and pumping water, and for creating the energy that will run the air blowers you will need to make a success out of intensive fish and plant raising on a commercially viable scale.  One of the cheapest ways of building your own power station is to build an anaerobic digester or series of digesters.  These make methane out of farm and human waste, which is ‘cooked’ by airless fermentation inside a large concrete vessel.  The resulting methane gas can be compressed and used to fuel  boilers for hot water and steam for electric turbines.  These days self-assembly anaerobic digester kits which do not need anyone with an engineering degree can be got for reasonable prices from China.  For further details, look up ‘anaerobic digester’ on http://alibaba.com.

Anaerobic digestion also gets rid of farm waste which would otherwise create a health hazard fairly rapidly.  This makes sure that your community live food bank is not also a toxic waste dump.  Ensuring your own food security should not entail creating a stink!  You need to get off the grid with your energy supply in any case, since an aquaponics system uses modest amounts of electricity 24/7.  You do not want your food security to be impacted by enormous electric bills.

Before going ahead and raising fish, find out which fish are popular already in your area and raise those.  It will be the vegetables raised in the fish waste water that make most of your profits, since fish take anything up to two years to get to plate size. So for the first couple of years, until you start harvesting your fish tanks in succession, you will be making your living off the plants, not the fish.  The fish will be too small to eat for most of that time.

Make sure that your fish tanks are seeded in succession so that you get a harvest of fish say, once every six weeks once they start to come on line. Work out how many tanks you will need to get that harvest coming in year-round, and how many vegetable raceways you will need to balance the nitrates in the system.  This is a complex calculation and will be referred to in my next How Much Fish Can An Aquaponic Farm Raise? article.

The nature of your community and the level of its commitment to farming locally and sustainably, creating local food security, will directly affect the size and success of your community aquaponic farm. You need to establish routines and standard operating procedures and stick to them.  Your local markets for your produce and fish will also have to be weaned off imported and artificially fertilized produce bit by bit. You can also expect to see an increase in the organic waste offered to your anaerobic digesters for recycling. This is free fuel for your aquaponics system power plant.  Food security depends on energy security, so training your local community to route organic waste to your digester should be a top priority in marketing your aquaponic community live food bank to all concerned..

Because aquaponic farms, properly designed and managed, can produce up to four times more food than an equivalent conventional farm on the same area, for far less inputs, you may eventually find that you can actually feed a lot of your local community members almost entirely from the produce, fish, and other food enterprises that you local community aquaponic farm has put in place.   For the food security your own community live food bank will provide over many years to come, everyone has to make a commitment to keeping up the pace of work on the aquaponic farm.

Apr 03

Aquaponics-Food Per Acre (0.5 Hectare).

lettuce growing at the aquaponics system of the University of the Virgin Islands

Intensive lettuce production in the UVI aquaponics system.

Aquaponics can potentially grow you much more food per acre than any other farming method.  However, it all depends on how well you manage and operate your aquaponic farm, and how dedicated you are to aquaponic farming.

Because you are farming in fish farm waste water, your crops are going to grow considerably faster, at higher planting densities.  But in order for this to happen, you have to look at and maintain optimum growing conditions both for plants and fish.

This is really vital.  You should make sure that your water quality and greenhouse or field temperatures are in the zone for growth, and not let up on your water testing and routine inspections of stock and equipment.  To get significant food per acre in aquaponics, you have to make sure that your growth parameters are under control, and that means strict attention to fish feeding charts, water quality control, and climate control (if you are using a greenhouse).

Since each plant species and fish species have different requirements, and work together differently, it is difficult to pontificate about this subject in general.  Each specific plant and fish type needs to be handled according to its needs, and according to your requirments for crop quality and fish size.  Different crops require different temperatures, different nitrate levels, and different care and pruning, etc. to give you maximum food per acre.  Lettuces (see chart below) are especially temperamental, and bolt if nitrate levels are too high, too low, if air temperatures are too high, etc.  Each plant type has its own personality that has to be catered for.

Biological pest control, the only kind possible in aquaponics, where you have fish growing in the same water as the vegetables, is another set of living creatures in the system that need attention and observation daily.  You want thriving populations of ladybugs (ladybirds in the UK).  This will keep down the aphids.  However, no aphids, no ladybugs.  The  likelihood of aphids completely disappearing once accidentally introduced is small, but you need to keep their numbers down and the ladybug is your critter for that.

Without adequate biological pest control, you will not get the food per acre or food per hectare that you require for your aquaponics business to succeed.

lettuce per hectare

Lettuce Production In Aquaponics

The above chart gives you some estimates for what is possible with just over a hectare (2 acres roughly) under aquaponics, just for growing lettuce.  However, to get results like the above you need to be a “black belt”  in aquaponics, with some heavy duty training and experience under your belt.  You can also get from three to seven metric tons of tilapia fish out of such a system, depending on how hard you are prepared to work on maintaining water quality for heavily stocked tanks of fish.

Lettuce does not need nearly the nitrate levels in the water that crops like say, tomatoes or peppers do.  So you do not have to stock your tanks so heavily, which is easier on the fish.  You can also control nitrate levels by controlling bacteria levels in the clarifier and filtration sections of your aquaponics system.  The more you rinse them out, the less nitrifying bacteria you will have in there, and the less the ammonia in the water will get turned into nitrate.  Don’t overdo this, because then high levels of undigested ammonia and nitrite will kill all your fish!

But then, the tilapia you are growing are also part of the food production volume per acre question.  It really depends on your local market for fish and vegetables, what you do.  However, it is more likely that you will make a profit on the vegetables that is worthwhile, rather than on the fish, which will probably just cover your operating expenses, as far as earning power goes.  Aquaponic farming makes most of its profits from the vegetables, not the fish.  But you need the fish to provide the miracle grow fertilizer for your aquaponic farming enterprise to succeed.

As you can see, there are many ins and outs for getting the water quality right for optimum growth conditions for fish and plants. To get the food per acre or food per hectare that you expect, you really need to read up on the finer details of aquaponic farming yourself.

A very good book, Aquaponics Q and A (The Answers to Your Questions About Aquaponics)
answering your questions about operating aquaponics systems commercially is now available by the doyen of commercial aquaponics, Dr. James Rakocy.

I highly recommend this as a compendium of problem-solving solutions which are also equipped with all the math and all the experience of a world-famous aquaponics professional, with a lifetime’s experience of real down-and-dirty aquaponic farming. Get the maximum food per acre or hectare possible with finely-tuned aquaponic farming!

Mar 19

Environmental Issues, Aquaponics, And Agriculture

The environmental issues surrounding conventional agriculture are well known.  According to http://savetherainforest.org, 60% of rainforest loss is due to landless farmers going in to farm along new roads opened up by loggers in the jungle.  This is because their land has been taken over by large concerns to grow crops for export such as soybeans, and also due to population growth in these areas.

There are other tales of soil destruction due to land overuse, which creates dustbowls, and due to the use of substances such as herbicides containing glyphosate, which destroy soil bacteria and distort soil structure in the long term.  For more about this go to the interviews with Dr. Huber of Purdue University, on http://mercola.fileburst.com/PDF/ExpertInterviewTranscripts/InterviewDonHuber-Part2.pdf, which is a transcript of the second part of an interview with him on mercola.com, the website of the world-famous Doctor Mercola.  Wikipedia also has scary entries about this substance if you look it up.

In between desperate farmers and the chemical assault on our soil and environment, which may well be causing other problems such as the disappearance of the bees, without which many crops will not fruit, conventional agriculture is reaching a state where the law of diminishing returns comes into play.

These environmental issues have spawned a rise in the adoption of organic farming, but the question here is that it is vulnerable to the very diseases and blights that are dealt with by the chemical barrage used by conventional agriculture.  As such, it may well not be able to produce enough food if universally adopted. It also takes up as much if not more space on the soil as conventional agriculture and is just as water-hungry.

The next environmental issues, to do with water use in agriculture, are also key.  Worldwide, we are running out of potable water at an alarming rate.  These environmental issues are caused by the fact that for the most part, water is used only once in conventional agriculture, then discarded.  It is hardly ever recycled since it is used to carry away waste and for cleaning, also for irrigation, which consumes whole rivers and lakes.  Due mostly to irrigation, the River Jordan in Israel no longer flows into the Dead Sea.  Many other bodies of water such as the Aral Sea have all but disappeared. ‘Formerly one of the four largest lakes in the world with an area of 68,000 square kilometres (26,300 sq mi), the Aral Sea has been steadily shrinking since the 1960s after the rivers that fed it were diverted by Soviet irrigation projects. By 2007, it had declined to 10% of its original size’-Wikipedia.

Lake Chad in West Africa is also rapidly disappearing.

The north of China is also rapidly running out of water.   It has already used up most of its fossil water resources, the underground aquifers that cannot be replenished by rain. I enclose a scholarly presentation about this vast problem:

However, in the midst of all this disarray, and a tide of misinformation from vested agricultural interests bent on selling more toxic chemicals and genetically modified organisms, purported to make conventional agriculture more efficient at vast expense, there are other less well known technologies which do not require any of these complexities to work, and once installed, are vastly cheaper and less water-hungry to run.

These technologies are all based on recycling water, instead of using it just once.  Recirculating aquaculture (sustainable fish farming) has spawned an offshoot called aquaponics, where plants are grown hydroponically in the waste water from the fish.  This waste water is cleaned by the plants, which absorb the nitrates dissolved in it and use them for exponentially faster growth than normally seen in conventional agriculture. This deals with several environmental issues at the same time.

These environmental issues can be listed as follows:

  1. Water is constantly recycled, and used again and again by the fish and the plants. Less than 10% of the water used by conventional agriculture normally to grow food is required. Evaporation is controlled by covering most of the water surface with floating rafts that suspend the plants in the fish water, and shading the fish tanks. These can also be provided with lids in some situations.
  2. Water pollution from fish waste released into the environment is eliminated completely. Removed fish waste solids are dewatered and used as organic fertilizer after composting. The water from this process is fertile and can be used for irrigation. Still 90% less water or less than conventional agriculture uses,  is required to keep the aquaponics system going.
  3. Toxic herbicides are unnecessary since there are no weeds to pull.  Only biological non-toxic pest control methods can be used, since all pesticides, even the so-called ‘organic’ pesticides based on the pyrethrum flower, kill all the fish dead fast. The chemical assault normal with conventional agriculture is stopped.
  4. Artificial fertilizers are not necessary or used. The fish water provides ample nitrogenous matter which is turned by naturally occurring bacteria in the aquaponics system, into nitrates that fertilize the plants in the aquaponics system’s hydroponic component.  The expense of buying in artificial fertilizers is avoided, and the pollution of fertilizer over-use, stopped.
  5. The space used is around half what would be necessary to grow food using conventional agriculture.  This means that you can grow up to twice as much food on any given acreage than would be possible using conventional agriculture. This does not even count in the harvests of fish that will be produced.  Due to the efficiency of hydroponic growing methods, plants can be spaced at up to half the spacing normally required in conventional agriculture.  They also grow at up to twice the normal speed for plants grown in soil. So you get up to twice as many plants, twice as quickly.  This is all dependent on the types of crops grown, but lettuce and basil can be managed professionally to grow at these rates, for instance, quite easily.  This has revolutionary implications for land-starved farming communities, especially since no soil is needed, so any flat surface can be used to grow food.  You can even grow food on a flat roof surface, in the city.
  6. Fish can be grown intensively on land with very little ecological footprint. The biofilter is the aquaponic system, so none of the notorious water pollution normal with intensive fish farming on its own is caused. This means that there is a possibility of reducing the pressure on ocean fish populations which is steadily wiping them out at present.  1/8 of an acre of aquaponics can rear 5 metric tons of tilapia fish a year, for instance.
Tropical aquaponics-lettuce crop in 29 days, University of the Virgin Islands, 2010

Tropical aquaponics-lettuce crop in 29 days, University of the Virgin Islands, 2010

In places like South America, West Africa and China, the wholesale adoption of this technology could spare the countries in these places further environmental issues, drought, poverty and desperation. However, there are only a limited number of trained and available independent consultants such as myself who are willing to undertake the consultancies necessary to set up demonstration aquaponics systems.

Call me! - Charlotte Appleton: Offline

» Get Skype, call free! I can be contacted for preliminary discussions via Skype for free.

These aquaponics systems should be set up professionally on a large enough scale to show how aquaponics can replace the methods of conventional agriculture.  Farmers can then be taught how to produce more food using 90% less space and water, and 17% of the energy currently used in conventional agriculture. They will learn that they need far fewer and far less costly inputs to do this than currently used in conventional agriculture.  These inputs mostly consist of fish feed. Aquaponics uses only non-toxic pest control and needs no herbicides.  If you liked this article, I have edited the past 6 months of this website’s posts into an ebook to download on the spot which is available here for only $10: [paiddownloads id=”1″]

To learn more about how aquaponics works, and how to make it work for you, I suggest you read a few of these books from the world’s leading experts on aquaponics and aquaculture:


 

Feb 11

20 Reasons To Use A Commercial Aquaponic System.

  1. Are you in greenhouse agriculture? Would you like to see the efficiency of your greenhouse be increased by hundreds of percent? By using aquaponics, among other organic growing methods, Will Allen of Growing Power in Milwaukee, in the United States, has grown a million pounds of food off three acres (1 ½ hectares) year on year. In the freezing cold. In the winter as well as in the summer.
  2. Are you spending more and more money on artificial fertilizers and replacement composts to grow the same yields? Aquaponic farming needs no artificial fertilizers. The fish in the aquaculture part of the system produce the fertilizer for the crops with the help of a couple of different types of naturally occuring beneficial bacteria. These nitrifying bacteria come free.
  3. Are your staffing and energy bills spiralling upwards? Aquaponics is largely automated agriculture. Staffing levels for a 1/8 of an acre system that produces 5 metric tons of tilapia a year and at least that in vegetable crops, are only 3 or 4 people for the technical management and a few extra casual staff weekly to help with harvesting.
  4. What about the water bills? Aquaponics uses less than 10% of the water normally required by agriculture to produce much more food per acre/hectare than conventional agriculture.
  5. Do you have enough water to really get the maximum production out of your crops or is your area (or country) getting increasingly arid? If you need to save water, aquaponics will help you do this and increase your yields at the same time. Aquaponic techniques make sure that most of the aquaponic system water stays shaded or covered to reduce evaporation of the water. Water in aquaponics is not used just once, but constantly recycled round the system.
  6. Are you on the edge of a desert? Is soil salinification a problem? Irrigated soils gradually become loaded with salts from artificial fertilizer applications in arid climates. This makes the soil less and less fertile, and it needs more and more fertilizer to do the same job. What are you going to do when the soil eutrophicates (becomes too loaded with salts to work)? You will need to install a system that sits on the soil, but does not use it. Aquaponics does this, and does not waste water. Most of the water gets recycled round the tanks of the aquaponic system.
  7. What are your heating bills for your greenhouses if you live in an area with a frigid winter? If you run an aquaponic system, you can use the offcuts and vegetable harvest waste to make compost. In a commercial sized system, considerable waste builds up, and as compost, it heats up. By piling compost heaps against the sides of your greenhouse to the required depth for the heaps to heat up (more than 1 meter x 1 meter) you can use the compost to reduce or eliminate your greenhouse heating bills.
  8. What do you spend on pesticides? Because fish live in an aquaponic farming system, you cannot use ANY pesticides. Even ‘organic’ pesticides based on pyrethrum (a flower) kill the fish dead very rapidly. Without the fish, no fertile water for your plants can be made. You need to get hold of friendly insects such as lacewings and ladybirds, which feast on greenfly, whitefly, blackfly, and thrips. There is usually an insect predator bred commercially to get rid of most of your pests. However, bacteria such as bacillus thuringensis also are bred and sold to get rid of your caterpillars. You can use these kinds of pest control, some of which will continue to breed as long as there is a prey species to feed on and your greenhouse or outdoor tropical aquaponic system is at the right temperature. In this case, you are getting pest control for free…
  9. Do you need another product just to break even? You do not only grow vegetables and soft fruit such as strawberries in an aquaponic system. You are also growing fish, if at a slower rate. If you take proper care of your fish, you will get a premium product which can be sold as sustainably produced antibiotics-free fish. You cannot use antibiotics on your fish since they will kill the nitrifying bacteria which convert the fish waste into plant fertilizer.
  10. Do you need more space to get a profit? With aquaponics, you may not need more space. It reduces the space you need between plants by up to half the normal spacing. That means you can grow more plants in the space you have. Plants like lettuce also grow twice as fast in a floating raft aquaponic system since all stress is removed from their roots. They like to have their roots swimming in liquid fertilizer. And unlike hydroponic systems that run on chemical fertilizer, most aquaponic systems do not suffer from fungal infections and pythium outbreaks, so more of your crop will come in perfect and sell at a premium price.
  11. What happens to your waste water? Do you have problems getting rid of fertilizer runoff? If you run an intensive fish farm, what are you doing about the gunge from the mechanical filters and the sewage from the fish? In aquaponics, you run it through a simple clarifier system and then out to the hydroponic element of the aquaponic system, where the plants use up the nitrates in the water. It goes back clean to the fish to be re-used and re-fertilized.
  12. Does your back ache from bending over the crops all day? In commercial aquaponics, crops are growin in net pots in holes in floating polystyrene rafts. At harvest time, or when the plants need attention, you just lift out the floating raft in question and put it on a couple of trestle supports.
  13. What do you use to control the weeds? There are no weeds in aquaponics. There is nowhere for them to grow.
  14. How much time do you spend digging and tilling? There is no digging or tilling in aquaponics.
  15. How many crops a year are you currently getting for all that work? You can get at least 12 crops of lettuce, for instance, a year out of an aquaponic system.
  16. How reliable is your cropping schedule? An aquaponic growing trough full of floating polystyrene plants at various stages of development works just like a factory production line, with expert management, of course!
  17. How often does the weather slow down or stop production? There are no droughts or floods in an aquaponic system. In a climate controlled greenhouse, you can increase yields even more, but in the tropics aquaponics works very well and reliably, all year, outside.
  18. How easily can you change out crops if prices suddenly fail for what you are growing? In aquaponics, since your crops are on floating rafts, you can remove crops which are no longer economic and rapidly replace them with ones which are. Crops grow extremely fast in recirculated fish water.
  19. How often do soil pests such as nematodes severely impact your crops? In aquaponics, the crops are growing in fish water, not soil. No soil, no soil pests.
  20. Can you grow up to 40% more than other farmers without spending as much on inputs? In a well-run aquaponics system, you can.

Below is a very good little book by the leading expert on commercial aquaponics, Dr James Rakocy, who has put his over 30 years of experience of this technology into a clear Q & A problem solving format:


Feb 09

Why Grow Head Lettuce In A Commercial Aquaponics System?

Well, aquaponics works even better than hydroponics, according to research done in Alberta, Canada. So you are going to get a lot more head lettuce a lot faster out of your mature aquaponics system than you would out of soil.

However, the advantages do not stop there. An aquaponics system produces crops on a ‘conveyor belt’ type continuous cropping system. This works well outside in the tropics, or inside a climate-controlled greenhouse elsewhere. It means you can get fancy lettuces all year at twice the amount, twice the speed you would in a soil based system.

Pest control is also safer and easierin an aquaponics system. You are not using soil, so soil pests such as nematodes have been eliminated before you start. If you have a problem with snails, sunfish will live under the rafts and they love to eat any snails that crawl within reach! Using friendly insects such as lacewings and ladybirds (ladybugs in the U.S.) means that the more greenfly etc. there are, the more your friendly insects will feed and breed, provided the conditions and air temperature are right for breeding. So you get more friendly insects for free! Of course, there is always the risk that your friendly bugs will feast themselves out of food, but that’s what you want. No more greenfly etc. To keep a reserve supply of friendly bugs, it may well make sense to have an on-site bug breeding station if you are in large commercial lettuce production. Otherwise, there are plenty of professional friendly bug suppliers out there who will send you bugs by the bushel in the post for spreading about your fancy lettuces with a camel hair brush.

Staffing costs are around 3 qualified and expert staff per 1/16 hectare aquaponics system, plus extra part-time semi-skilled staff for harvesting and tilapia fish processing as necessary. Because you have a 24/7 ‘conveyor belt’  floating raft system, which produces batches of marketable vegetables (fancy lettuces, for instance) once a week, you need temporary harvesting staff on an ad hoc basis. Once the aquaponics system is up and  running efficiently, around 8 weeks from pressing the on button, you will get set amounts of vegetables such as fancy lettuces  ready to harvest out of the system. You will need extra semi skilled labor who are trained in personal hygiene to handle these harvests (once a week, ALL YEAR ROUND). The tilapia fish come on line at table size six to nine months later to be harvested every six to twelve weeks depending on the number of tanks in use. Before that the fish have been growing from babies to adults and fertilizing the water for the plants. No back-breaking work is necessary since the vegetables are grown in fish water on floating rafts. These are lifted out entire onto trestle tables (see picture of lettuce harvest at the commercial aquaponic system University of the Virgin Islands below) and the vegetables harvested at table height.

The tilapia fish only pay your operating costs, since they grow much more slowly than lettuce. Lettuce seedlings take 29 days to grow to marketable size in an aquaponic system. This means you can have at least 12 harvests a year, or more if you seed and harvest smaller quantities of head lettuce or fancy lettuce every week.

Lettuce production compares favourably with other vegetables such as cabbages, which have longer growth periods and lower price points at sale. To recoup the cost of installing your aquaponic system, you need to get the maximum profit per crop and as many crops as possible per year.  Therefore you need to grow crops such as fancy or head lettuce which, with their 29 day grow out period, reliability, marketability, and high market wholesale price for quality organic produce, make commercial sense.

Other crops with short grow out times and marketability such as basil also make sense, as long as you have a high local demand for it. There is no point in growing food you cannot sell immediately at a good price and in sell-out quantities!  Head lettuce fits this bill. So to begin with it is advisable to go in for lettuce production. Don’t forget that after the first six months or so of lettuce production you will also have to market the tilapia from your fish farming.  It is best to get good at marketing two main products before you diversify.  This is not a hobby and you cannot afford to muck about with experimental products at the initial stage.  Stick to a small range of products such as head lettuce which have guaranteed marketability and local demand.

Productivity in a commercial aquaponic system depends to a large extent on professional and trained management who stick to the requirements of a well-thought-out standard operating procedure for this form of agriculture. This should integrate fish farming and hydroponic vegetable production properly. The unreliability due to weather and pest attacks that characterizes soil agriculture has largely been eliminated.   Pest and diseases are usually amenable to properly exercised biological pest control. It is only human error, ignorance and neglect that can ruin your lettuce production, tilapia fish farming, and impact the profitablity of your aquaponic farm overall.  It is here that the need for proper professional training and experience will make itself known very rapidly.  Aquaponic farming is not a just add water agriculture technology.  You need to know how to keep fish, especially tropical fish, and how to grow vegetables both organically and in an aquaponic hydroponic system.  This is NOT the same thing as hydroponics using chemical solutions. Not at all.

If you have a greedy market locally for fancy lettuce, it may well be to your benefit to invest in a reliable commercial aquaponic system and training in this form of agriculture.  You need the right trained  staff and the right equipment to get started with your commercial aquaponic farm. Several tons of fancy lettuces a year can be grown on only one-eighth of an acre (1/16 of a hectare), along with five metric tons of tilapia fish a year from your aquaponics-integrated intensive fish farming efforts. Given the right attention to detail and diligence, of course!

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harvesting aquaponic lettuce from a floating raft

Harvesting aquaponic lettuce from a floating raft, UVI, 2010