Aquaponics: Fish, Water and Plants
A closed system of life
It was cold and snowy the day I visited Victory Aquaponics in Londonderry. But inside the barn-like greenhouse, built by owner Ross Williams, it was spring — warm and filled with various shades of green.
Light filtered through the plastic sheeting and about 30 different varieties of leafy greens thrived in the diffused brightness. But their roots are not in soil, or even peat moss. The plants, floating in Styrofoam mats, are growing their roots in water, rich in nitrates rather than chemical fertilizers. The enrichment comes from 14,000 gallons of water pumped up from a lower level, which is the heart of the operation — a host of blue plastic tanks swimming with tilapia and goldfish.
Hydroponics is the process of growing plants in water, but aquaponics is a hybrid technique that uses the rich effluent of fish to provide the nitrogen needed to feed green, non-flowering plants. Williams built his greenhouse with a substantial lower level to house a demonstration garden, plant nursery and space for a half-dozen or so large, blue plastic tubs to hold the fish. He feeds the fish grain every two hours. They swim in circles and aren’t harvested for food — yet.
Williams, a native of New Zealand with a delightful Kiwi accent, was a bit tired on the day of my visit. He had spent the night at the greenhouse to make sure the storm didn’t take a toll on the roof, and that the power to run the heat and fans didn’t stop. An incident like that could easily ruin this crop and set back his six-year investment in the process. He had designed and built the greenhouse for aquaculture’s unique demands.
The idea for the farm started with his son Gavin’s research. He’d looked into how to keep his fish tank clean and discovered that fish and plants form a perfect synergistic circle. What the fish put into the water, the plants remove, and the water is then clean. When Williams was looking for a business, a large-scale translation of that fish-plant synergy seemed a natural fit for his technical and farming background.
Williams has worked over the past several years to perfect the system, sharing his hard-earned information with whoever is interested.
The whole process is a delicate balance with plenty of complexity. The nitrites from the fish are converted by naturally occurring bacteria into plant-usable nitrates. The natural expression of bacteria is part of the process. It turns out that you can’t put mature fish in the water — they need to be young. Williams learned much of this information along the way through trial and error. Though he cannot advertise his produce as organic, the harvested greens are about as pure as possible, with no need for insecticides or chemical fertilizers. To speed growth, he has invested in LED lighting to supplement light in the winter; New England winter days are just too short.
Williams sells kale, butterhead lettuce, bok choy and microgreens at the Salem Farmers’ Market in both winter and summer. Along with the produce, Williams also brings dozens of eggs to the market, thanks to his flock of free-range chickens. The eggs are not part of the synergy of the aquaculture, but they do get to feed on greens when available. They like it — and you should too. If you won’t listen to your mother, take the USDA’s word for it: dark, leafy greens are the heart of good nutrition.