Friday, October 31, 2014

Aquaponics 101

A ripe jalapeƱo and happy koi fish living in symbiosis.
This prototype is our first step in developing a much larger system.

Have you heard of aquaponics? When we learned about aquaponics it changed our lives forever. Aquaponics is a novel system where gardening and fish farming are combined into one! Conventional fish tanks rely on disposable filters and repeated flushing of water to reduce toxic levels of ammonia. Likewise conventional gardens tend toward a nutrient deficiency that must be counteracted by regular application of fertilizers. There's no winning in either game because inherent tendencies throw the systems out of whack without regular intervention. Happily these two tendencies can be set into balance by combining the two into one integrated whole: Aquaponics (aquaculture + hydroponics). Aquaponic farmers capitalize on nutrient rich fish waste by converting it into plant food, using a culture of beneficial bacteria and worms. The result is an inherently balanced system that mimic nature's own cycles.

How it works

A typical hydroponics system

A typical hydroponic system consists of a fish tank with fish, a growing bed that contains an inert growth and filtration medium such as gravel, a pump on a timer that runs about about once an hour, worms and bacteria that live in the grow bed media, and a testing kit for monitoring the system (ph, ammonia, nitrites/nitrates). Most of the time the pump isn't running and the grow medium is wet but permeated with air, just like soil.

The key to aquaponics is the culture of microbes pictured in the magnifying glass above. The microbes convert ammonia into nitrites and nitrates. They convert the toxic waste produce by fish poop into plant food. An appropriate environment must be set up to support these bacteria. A large surface area with highly oxygenated water makes the perfect home for the microbes. PH plays an important role in the health of these bacteria as well. Finally the red worms provide an added stage of decomposition, mechanically breaking down the fish waste into a more digestible form for the microbes.

If you're interested in getting into aquaponics I highly recommend the book Aquaponic Gardening: A Step-By-Step Guide to Raising Vegetables and Fish Together. This book alone taught us everything we needed to build the system pictured above.

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