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"Aquaponics is a food production system that combines conventional aquaculture with hydroponics in a symbiotic environment." (Wikipedia) By combining these two systems farmers are able to increase their yield, decrease costs and deal sustainably with some of the challenges of hydroculture. In aquaculture the buildup of fish excretion causes toxicity over time, however, nitrates and other products of excrement can be used to feed hydropic growing systems, which in turn clean the water.

Aquaponics Raft MaterialsThe ECHO Global Farm in Florida has a well-established aquaponics demonstration built using the "Use what you have to build what you need" ethos of Appropriate Technology. ECHO staff and interns have been experimenting with the long-term viability of materials that can replace the traditionally used polystyrene as a floating plant support. Polystyrene is not always affordable or readily available, and comes with its own set of concerns about long-term exposure. Rafts have been tried using bamboo, used PVC and drip tape, and waste plastic water bottles to good result. (Pictured)

Craig Bielema (ECHO Appropriate Technologies) says that having the demonstration on the farm allows additional experimentation. Several leafy crops have been used as food supplements for the fish including Chaya and Okinawa Spinach. "Our tilapia ate the Chaya, but wouldn't touch the spinach," says Craig. "For small-scale farmers interdependent systems like aquaponics can be difficult to measure and test, however we have learned that in this case if you've got a problem, if something is out of balance, either the fish or plants will tell you." For example, in the hot Florida summers the fish can be seen piping, or pulling oxygen down into the water with their mouths. When the staff sees the fish spending too much time at the surface they know that it is time to increase the water's oxygenation, which can be as simple as increasing the water flow or height from which it falls.

If you are interested in using or training in aquaponics the 22nd annual ECHO International Agriculture Conference in November will feature a plenary session and hands on training by Phil Reasons. With over 40 years of agriculture experience Phil is the Executive director of Morning Star Fishermen and a consultant on the ECHO aquaponics demonstration. [ Registration Open Now ]

More Resources

ECHO Asia Notes #22 features a Cement Ring Aquaponics System