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Fish for thought

Young scientist switches focus from pre-med to agriculture, and sees fish in new light.

Zak Buell changed his career track from pre-med to sustainable agriculture.

Zak Buell changed his career track from pre-med to sustainable agriculture.

Photographs by M.O.D. Media Productions

(page 1 of 2)

From the pages of In Business magazine.

Tucked in the hillsides around Belleville, Wis., Clean Fresh Food is growing leafy greens in a way most farms don’t … without dirt. The business practices aquaponics, a method of growing nutritious food without soil.

Associate Scientist Zak Buell, 25, explains. “Aquaponics combines aquaculture and hydroponics (growing plants without soil) in a way that eliminates the downsides of the practices separately. It’s a brilliant innovation, really.”

Hydroponics, he says, is completely reliant on chemical fertilizers and is not self-sustaining, while the most common complaint in aquaculture centers is the amount of waste leftover from fish.

Yes, fish.

At Clean Fresh Food, aquaponics is the key to growing delicious, leafy greens using nutrients derived from fish waste.

Here, a small staff attends to thousands of tilapia raised from young fry to maturity in a system where healthy bacteria break down fish waste. The result is a nutrient-rich liquid perfect for growing varieties of lettuce, herbs, and micro greens year round.

Mike Knight and his wife, Dagny, launched the operation in 2012 and celebrated its first harvest in the summer of 2013. [If the name sounds familiar, Knight founded and later sold Third Wave Technology Group.]

Buell joined the operation less than a year ago. “Our goal is to produce food environmentally in a healthy, clean way using no chemical additives,” he says. “We take great pride in providing fresh food to our clients.”

It’s a fascinating, natural process.

Hardy and healthy

Above, lettuce roots thrive under floating rafts until harvest.

Inside the bio-secure fish house, 12 1,200-gallon water tanks bubble from aeration. Each tank contains between 100 and 150 tilapia purchased as small fry from fish farms. They will grow to adults weighing five to seven pounds, on average.

“We like tilapia because they’re hardy, they grow quickly, and they can handle Ph changes,” Buell says. The downside is that Clean Fresh Food does not have the certification or staff to clean and filet fish prior to selling to restaurants or stores. For that reason, it is considering switching to bluegills or yellow perch because of their popularity and marketability. “We may test the waters this summer,” he adds. “There are plenty of people willing to filet a bluegill.”

As the fish live and grow in the tanks, the excreted waste gets filtered out, leaving behind a nutrient-rich cocktail of nitrogen, phosphorus, and calcium. Buell adds potassium carbonate and agricultural lime to boost the mix.

The aquaponics system is gravity-fed. Well water from the property moves through the fish tanks into a mechanical filter where bio media resembling macaroni noodles are churned a couple times a week to physically break down the waste.

“The mechanical filters, and essentially every other submerged surface, acts as a home to our beneficial bacteria,” Buell notes. “They are essential in converting toxic components of fish waste — primarily ammonia — into an inert form that is more useful to the plants.” Excess wastewater is diverted to a retention pond on the property and used to fertilize crops during the warmer months, but the payoff is in the greenhouse next door.

It’s an ah-ha moment.

Floating ecosystem

Inside the brightly lit space, varieties of green, leafy lettuce, herbs, and micro greens thrive in contrast to the gray landscape outside. Filtered water flows through six long, rectangular troughs, each about 150 feet long and 10 feet wide. Plants float in Styrofoam rafts poked with holes for root growth.

Many varieties of seeds are germinated in the fish house before being moved to the greenhouse. When they’re ready to transplant, Buell puts them in a spongy substance called Rockwool and plugs them into a raft hole where they will continue to grow until harvest. It could take as few as two weeks or as many as seven.

The water meanwhile, recirculates to the fish house.

“We do our best to maintain a completely circulating system and only add about 2,000 gallons of water a week,” Buell notes. The system is remarkably efficient, with electricity needed only to power a sump pump and a few grow lights above. Meanwhile, heat piped in from an outside wood burner warms the well water as necessary.

Buell regularly monitors Ph and checks levels of ammonia and dissolved oxygen. “Checking the water chemistry alone could be a full-time job,” he admits.


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