Happy Dancing Turtle (HDT) recently received a grant for expanding hydroponic and aquaponic production in central Minnesota.
In hydroponic and aquaponic systems, plants are grown in nutrient rich water pumped through a bed of baked clay pellets rather than soil. Aquaponics differs from hydroponics in the way nutrients are added to the water. Hydroponics require powdered nutrients to be mixed into the water; aquaponics does not. That’s because the nutrients are taken care of by a tank of farmed fish.
“That’s what’s nice about the aquaponics is you don’t have to add fertilizer because the fish waste is the fertilizer,” said Dave Wilson of HDT, who is in charge of managing the home scale systems being used on the HDT campus.
HDT received the grant from the University of Minnesota Central Regional Sustainable Development Partnership. HDT is participating with various other groups throughout the state to experiment with aquaponic and hydroponic systems that could realistically be used in commercial or home settings.
“The University Regional Sustainable Development Partnership wants to connect the university to the citizens and show what the university is doing and how they are helping local citizens to develop economic and environmental systems,” said Jim Chamberlin of HDT.
“We got a grant from the regional partnership to study this and look at some of the larger, more commercial operations in hydroponics and aquaponics. The outcome is supposed to be a written report of the different projects,” Wilson said.
“Hopefully we’ll have that information that we can publish for people who are interested in getting into it on either a commercial scale or home scale.”
Through the partnership, HDT will be able to access data from other groups measuring the return of investment from other hydroponic and aquaponic systems to determine feasibility for different commercial and home scale operations.
Using mostly materials already available to them, Wilson and other staff members built a deep water culture hydroponic system and a flood and drain aquaponic system. The systems will be used to produce plants side by side in identical settings. That way they can have their advantages and disadvantages compared. These systems are also compared to traditional growth methods.
“The advantage of hydroponics is you can extend your growing season, doing it indoors in the winter. You can also maintain the proper nutrients that your plants need and you can grow things a lot faster with hydroponics than soil,” Wilson said.
Wilson said plants grow 30-50 percent faster in a hydroponic system compared to a traditional garden. This is because the system pumps oxygen into the water. In addition, the system has little risk of insects, no weeds and less risk of contamination by bacteria like E. coli.
The HDT aquaponics program has two large water tanks — one filled with tilapia and one used for growing duck weed to feed the tilapia. Red wiggler worms from the HDT vermicompost system are also used to feed the tilapia. Some of the worms are added to the clay pellet growth medium, which keeps the medium clean and adds more nutrients to the system.
“It’s a good revolving system,” Wilson said.
Another difference between the hydroponics and aquaponics systems is that the hydroponics system requires close scrutiny, otherwise the pH levels of the water could harm the plants rather than nourish them. In an aquaponics system, pH is controlled by a natural system of beneficial bacteria. These bacteria consume ammonia from the tilapia to turn it into nitrites, while another bacteria consumes the nitrites and makes nitrates.
“The nitrates are a useable form for the plants,” Wilson said.
Like a home aquarium, the hydroponics and aquaponics systems must regularly have about a third of their water removed and replaced with clean water to prevent the buildup of unwanted wastes.
Hydroponics and aquaponics can produce a lettuce crop every 24 days. Aquaponics can also produce edible tilapia within 8-9 months. Other plants can and are produced in these systems, though lettuce is one of the simplest.
So far Wilson’s system is about a month old and the bugs are still being worked out. Temperature is perhaps one of the biggest problems so far. Tilapia like 70- to 80-degree water, so Wilson is experimenting with customized tank heaters to control the water temperature.
“The project is supposed to run through May, so through the winter we’ll keep it running for sure and see how it’s working. I don’t know if we’ll try to keep it running through the summer or just run it in the winter. We’ll have to see how it all works out,” Chamberlin said.
By the time the project is complete, Wilson and Chamberlin may have experimented with more styles of aquaponics systems, including systems that are outdoors, or wick systems better suited to root crop growth. In a wick system the water is drawn to the plant’s roots by an absorbent material such as cotton rather than having the water pumped into a tank where it pools around the roots.
“One thing nice about hydroponics or aquaponics — there’s no set-in-stone way the design has to be,” said Wilson. “You can just make it your own and come up with your own way you want to do it and it’s a kind of open for a lot of improvements and things can get easier and cheaper.”
Aquaponics systems require approximately 250 gallons of water to make pH and nutrient levels more constant. The system also requires water pumps, aerators, tank heaters, a growth medium and grow lights.
Aquaponics and hydroponics have been growing in popularity since the 1970s. Aquaculture, or aquafarming, has been used for several hundred years to produce farmed fish. Experimental and commercial aquaponics and hydroponics systems are currently being used in many places, including Staples, Duluth, Silver Bay and countless other areas throughout the country.
“It’s kind of surprising the amount of our food that already comes from hydroponics,” said Chamberlin. “There’s more out there than you would think there is.”