Scott Henley wanted to prove he could turn the backyard of his modest Pasadena (Los Angeles) home into a working farm. “Part of the experiment was could you potentially have your typical family- 2 working adults, children-, could you make a small lot like this- this is 8,000 square feet- produce enough to eliminate the need for one of the parents to go to work someplace.”
Aquaponics for efficient small space gardening
To turn a conventional backyard into a productive farm, Henley turned to aquaponics- a combination of aquaculture (fish farming) and hydroponics: “This is a very efficient way to grow things in a small space. And it also produces a protein source.”
He farms tilapia because they breed fast. The fish waste is broken down in the water by naturally-occurring bacteria into nitrate. The plants take up the nitrates as food and the now-cleaned water is fed back to the fish and the process begins again. The only inputs are sunlight and fish food. It’s an inherently organic system because any pesticides would upset the natural balance of the small ecosystem.
DIY aquaponics: hardward store materials
Henley built his set-up using only materials you could find at a hardware store. His plants grow in rafts: he uses 3/4 inch plywood covered by fiberglass and resin and styrofoam roofing insulation. He uses three air pumps to keep the water moving. The pumps total 1.7 kilowatts and he estimates the cost to run is about 20-30 cents per day.
To heat the water- the tilapia being tropical fish like warmer water- he relies on passive solar (the water runs through black irrigation tubing that heats up during the day).
Matching fish and plant ecosystems
The fish like water between 82 and 86°F, but his plants (lettuces) prefer cooler water. This is just one of the incompatibilities between his plants and fish: the plants like a more acidic pH, fish like a more alkaline so he aims for a neutral pH. In order to improve upon incongruencies like this (the plants also prefer a more acidic solution, fish more alkaline), he is changing the type of fish he uses. He’s setting up his garage to breed minnows: he’ll feed the minnows to the tilapia and run the tilapia as a pure aquaculture operation.
After less than 2 years in operation (he started in the summer of 2012), he- through Whisper Farms– now sells enough produce to restaurants, CSAs and at the local (Altadena) farmer’s market- to cover all costs and produce a small profit. His “experiment” is still not productive enough to create a salary, but he hopes that will change once he’s able to sell his fish and create more of a cooperative setup with other farms (to reduce the permitting costs for selling at farmers’ markets).