Go With the Flow

Self-watering, self-fertilizing and small, aquaponic gardens are ideal for island living.

In his neighbor’s backyard in Makakilo, Thomas Grass inspects the 16-square-foot grow bed they share. Inside it, lettuce, tomatoes, watercress and taro rise from black cinder. A Zen-like trickling of water, with the occasional splash of a fishtail, are the only sounds the system makes.

It’s called aquaponics—a hybrid mix of aquaculture and hydroponics—and it’s being used in Hawaii backyards and on lanai, as well as by UH Manoa, HPU and Punahou School, which all have programs or do research on aquaponics. Like hydroponics, which grows plants in water, aquaponics does not require the use of herbicides because soil is not involved. But unlike hydroponics, aquaponics does not require artificial fertilizer—the fish do that dirty work. 

While you can go as small as a 10-gallon size, Grass’ system features dual 250-gallon aquatic tanks, which house red tilapia. A series of PVC pipes channels the water and fish waste from the tank to the plants, fertilizing them. The plants filter and oxygenate the water, which is piped back to the fish. It’s a symbiotic relationship, and fruitful: Aquaponics produces vegetables quickly, cutting the growing time of plants in half, and only uses about one-tenth the amount of water that traditional farming uses.

If you’re interested in getting started in aquaponics, Olomana Gardens offers a class on Saturdays; call 259-0223. For supplies, stop by Waimānalo Feed Store (41-1521 Lukanela St.), which carries grow beds, pumps and even tilapia. You can also join the discussions and get tips at the online forum Aquaponics in Paradise, at aquaponicsinparadise.com.