Lettuce seedlings in the UVI aquaponics floating raft system.
University of the Virgin Islands commercial tilapia aquaponics system
To any ambitious biology or business teacher, a small commercial aquaponic farm is a priceless gift. In any large flat roofed school building, you can have one on the roof and the students can run it as part of their classes, since it is automated largely. But keeping an eye on the aquaponic organic food factory on the roof will teach them more about real biology, farming and agribusiness than any number of textbooks.
It may also provide the school with a much needed source of income in these interesting times.
But what is aquaponics? Aquaponics is intensive fish farming in tanks married to intensive vegetable farming in tanks. So you should know all about fish and plant biology as it applied to intensive aquaculture and hydroponics. This gives your students first-hand experience of looking after a natural ecosystem in an artificial container. You also should know how to keep the water quality good enough to suit the plants and the fish. Chlorinated water cannot be used, since the disinfectant in the water kills the bacteria that make the fish waste into plant food, see the diagram below.
Aquaponics system biology flowchart
Fish excrete ammonia. Nitrifying bacteria in the filter part of the aquaponic system convert the ammonia to nitrates. The nitrates are absorbed by the plants, and the plants grow really fast. This makes the water clean. The water is pumped back to the fish to be used again.
In aquaponics, only 1.5% of the water is lost in a properly designed and run aquaponics system. So it is very good for saving water on the farm. In aquaponics, plants can grow up to twice as fast at half the usual spacing. So you get up to twice as many plants, twice as fast, compared to farming in soil. But this can only be done if you have the right aquaponics system and the right training. As with any business, proper management is very important.
You will also need to know how to run and clean water pumps, air blowers, and alternative energy sources such as wind and solar generators. You need a cheap source of electricity to run the machinery of your automated aquaponic food factory on the roof.
YOU DO NOT NEED SOIL IN AQUAPONICS. You only need water. And you do not waste any water.
Because you do not need soil, only tanks of water, you can do aquaponic farming anywhere, like on the school roof, as long as you have electricity and somewhere to put the tanks, the pumps, the air blowers, and the plumbing.
In the tropics, you do not need a permanent greenhouse, though in places like Hong Kong where the temperature goes down a lot in winter, you will need temporary plastic hoop houses to cover your aquaponic systems and also to protect them from typhoons. These have to be quite strong to keep the wind and rain off the system. For example, lettuces do not do well in temperatures below 10 degrees centigrade and above 20 degrees centigrade they start to die.
Pictured below is a gravity feed version of a small aquaponic system. You would need something larger than this to make the farm economically viable, but this give you a basic idea of what can be done with recycled materials and a tank or three.
Usually the first fish you use to make the fertilizer for your plants is the tilapia fish from the Nile originally. It is one of the most commonly farmed fish in the world. It is a tropical fish and does not stay alive in water below 19 degrees centigrade or above 30 degrees centigrade. You will need someone on your team who has kept tropical fish before and knows how to look after them! If you live in a cold climate you will need to have some equipment to heat the water to the proper temperature and keep it that way.
Gravity feed aquaponics system
No fertilizers or pesticides can be used in an aquaponics system. They kill the fish! Instead, the fish water contains the nutrients that the plants need, and the pests can be controlled using biological methods.
Biological pest control methods include using friendly insects such as lady bugs to eat up all your aphids, also called greenfly. There are also parasitic wasps and lacewings which also eat other pests as well. You can buy these online and they come in suspended animation in little blister packs. You spread them out with a camel hair paint brush so as not to damage them, and lift them onto the areas where the bad insects are eating your crops. That’s it!
Another way to get rid of pests such as caterpillars is to use a bacterium called bacillus thuringensis. This comes as a white powder which you spray on. It makes the caterpillars sick so they die, but is harmless to fish and people.
Here are some aphids and the ladybugs that like to eat them:
Aphids eating a plant
You can also use harmless fats and oils to drown the insects that are eating your plants. But no insecticides or pesticides. They really do kill the fish, even if they are labelled ‘organic’!! You can be sure that none of the children will get poisoned by aquaponics for schools.
There are no weeds in aquaponic farming systems, so you do not need to use herbicide. So aquaponics for schools is not a toxic or dangerous activity.
There is no digging in aquaponics, and you can put the grow beds and raceways for the floating rafts up on tables and stands, so even people with bad backs can and do farm with aquaponic systems.
You can do all the work you need to do, including regular testing of the water to make sure the pH and other factors are correct, in a few hours a day. Your aquaponic systems are low tech mechanical systems with fish and plants growing in them. You have to make sure the fish and the plants have the best growing conditions. This sometimes means adding garden lime or potash to the water in tiny measured quantities to make sure that the water stays at a pH of around 7.0, or neutral. This is something to do for your biochemistry classes. Looking at the kH and hardness of your water supply and other features of water quality analysis will give them lots of practical experience of how classroom work applies in the real commercial world of fish farming and modern recirculating aquaculture.
But before you go ahead and construct your own school aquaponics system, you need to look at all the business side of aquaponic farming in your area and do a business plan. If you cannot sell your fish and vegetables, you should not grow them! Aquaponic systems can produce up to four times as much food for the space used, compared to conventional soil farming. 1/16 of a hectare of rooftop space can produce around 5 metric tons of fish and up to double that of vegetable plants a year. That is a lot of food to not be able to sell locally! Schools that have their own aquaponic systems need to be sure that they are not going to have a lot of food that is simply rotting on the roof. This is also very intensive fish and vegetable farming.
Market research is the first thing you do when you want to start a business, and aquaponic farming is a business. Aquaponic systems are very efficient food factories if properly managed and operated. This is something really interesting to do for your business class as a project. From your market research in local shops, markets and restaurants you can work out how much food you need to grow to cover the expense of constructing and operating a commercial aquaponic farm on the roof of your school. So then you can work out if there is enough room on your school roof for a big enough farm to cover your costs and perhaps make a bit of a profit. Aquaponics for schools is not aquaponics for fools!
If you are considering this kind of small commercial aquaponic intensive fish and vegetable farm on your school roof, please get in touch with us here
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and we can help you set this up correctly over Skype for a reasonable fee. If your farm is very big, it might be worth your while for a consultant to come and oversee the installation of your farm and the first few months of the business. Aquaponics for schools can become aquaponics for whole communities. If you get the whole community involved in their intensive fish and vegetable farm on your school roof, the sky is the limit!
Aquaponics Global Anthology 1 is available for instant download and to print out here: [paiddownloads id="1"]