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Lessons Learned from a Year of Aquaponics

Part 2: How Aquaponics Works In Spite of Everything

by Scott Beuerlein, Horticulturist

How It Works

So before we go into the “lessons learned,” which will be our final installment, here is a quick briefing on how aquaponics works. Aquaponics is a closed loop agricultural system in which fish are raised in a tank. Water from the fish tank is continuously pumped up to a bio-reactor, which is a fancy word for a small filtration system that mainly houses bacteria; that bacteria converts ammonia from the fish waste into forms of nutrients for plants; water exits the bio-reactor and is dispersed through trays housing plants, which take up the nutrients. The water then falls back into the fish tanks so clean that it makes for happy, healthy, hungry fish. We feed the fish and thereby keep the whole cycle going.

One of the 200 gallon fish tanks in the Aquaponics Greenhouse.

One of the 200 gallon fish tanks in the Aquaponics Greenhouse.

Our system is in a small, 12’ x 25’ greenhouse divided into two sides of two trays each. One side consists of a tray with hydroton, which is expanded clay balls, ($300.00, available from hydroponic suppliers), the other tray is a raft bed, made from foam insulation that floats on the water. Plants are stuck into 1” holes in the foam so their roots hang in the water. The other side is the same, except we substituted ordinary limestone gravel ($15.00) for the hydroton. Air is pumped into the fish tank, the bio-reactor, and the raft tanks. The only inputs are fish food, small amounts of a few nutrients, organic pest controls like insecticidal soap (used sparingly), electricity for the pumps, gas for the heating system, and water.

Happy plants in the grow beds of the aquaponics system.

Happy plants in the grow beds of the aquaponics system.

Why It Works

As a horticulturist who has studied roots and soil and how air and water and nutrients all work together to make plants grow, I still consider aquaponics a weird kind of alchemy. I cannot wrap my head around the idea that roots, which would rot at the drop of a hat in wet, mucky soil, can thrive in a tank of water. Sure, I know there’s plenty of oxygen in that water, and, true, without soil there are no soil-borne pathogens in the system, but, still, sorcery of some kind or other must be at play!  But that kind of thing has never bothered me very much—could never understand why Darren held onto his ideals with such a blind death grip on Bewitched and didn’t just go with the flow. Seriously, a twitch of the nose and you’re living the dream on the French Riviera? Fool! He caused so much stress in their lives. Anyway, fact is, aquaponics works and it works pretty darned good.

In our next and final episode, we’ll reveal the “Lessons We Learned”, which, although fulfilling, will leaving you wanting more.

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