November 22, 2013 by
Photography by Bill Sitzmann

Colton Allen, a seventh grader at King Science and Technology Magnet Center, counts the tilapia swimming circles in the horse trough. “Eleven?” he guesses. “Twelve?” It’s difficult to say, since the “tank” of his class’ aquaponics system is solid black.

“The system can take more,” explains magnet facilitator Kristine Denton, “but this is our let’s-make-sure-they-survive phase. Later today, we’re actually getting perch.”

“What?” Allen says. “I gotta be here for that.”

Is there a benefit to having perch versus tilapia in an aquaponics system?

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Raising seedlings, monitoring pH levels, and designing tanks that will keep the fish from ending up on the classroom floor are all responsibilities of the seventh-grade service-learning class at King Science Center.

“I don’t know yet,” Denton admits, laughing. “We’re going to find out.” Which is appropriate. The theme of King Center, one of Omaha Public Schools’ 19 magnet schools, is, after all, inquiry.

The food-growing system that holds pride of place in her seventh-grade service-learning class is the result of Denton’s desire to find “a really cool project that would get my students tied with the community.” In 2011, she attended the UNO Service Learning Academy, a weeklong program connecting public school teachers, professors, and the community, and discovered the aquaponics systems of Whispering Roots. She partnered with Greg Fripp, founder of the food education nonprofit, to bring the concept to her school, “and it’s been great ever since.”

Three years later, Fripp still supplies the fish and helps troubleshoot a system that’s not complex but is all about balance. “These kids are engaging with next-generation technology,” says Fripp. “You try to teach pH levels at the board, and their eyes glaze over. But if you point out that it’s a life or death issue for the fish, then, yeah, they’re engaged.”

DeAjai Philmon, an eighth grader, describes the concept of aquaponics with ease.

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The wastewater from the tilapia, she explains, is laced with ammonia, goes up a PVC pipe and dumps into a shallow wooden box of untreated 2x4s lined with plastic. Bacteria growing on the marble-sized clay balls that cover the plant roots in the box convert nitrites from the fish waste into nitrates, a fertilizer for the plants. About twice an hour, the box—essentially a gigantic biofilter—drains cleaned water back down to the fish, completing a cycle that encompasses water filtration, fish farming, and vegetable production. The most expensive parts of the system, Denton says, are the UV lighting that hang just above the plants and the heater that keeps the 100 or so gallons of water at 78 degrees for the tilapia.

“The plants are getting all their nutrients from the fish water,” Denton says. “You don’t need soil, you need the nutrients that come from the soil. Or in this case, the nutrients that come from the fish.”

The iceberg lettuce in this box is about two weeks old. “We harvested recently so we replanted seedlings,” Denton says, pointing to a set of six trays under grow lights. “We have some radishes, and we’re going to try peppers. We’re also going to try peas.” They’re climbing peas, so the kids will have to figure out how to give them proper support. “That’s like 90 percent of it,” she says, “figuring things out.”

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“Excuse me, Ms. Denton,” says Armani Price, also an eighth grader. “Is this basil?” She points to a tiny seedling with only a couple true leaves. Price says she’s getting better at identifying plants. She also assists with the school’s urban farm where she’s helped grow collard greens, jalapeños, bell peppers, tomatoes, watermelons, “and we did have a peach tree.” She’s discovering that fruit trees aren’t very easy.

Price and Philmon were part of the class that helped finish building the frame that holds the bed’s grow lights. Students are 100 percent involved in building structures, Denton says, as well as being in charge of crop rotation, water testing, and fish care. »
« “They’re responsible for making sure we have seeds and letting us know if we need to reorder.” Grants are in place for them to purchase supplies.

“We want to start a salt water system, too,” says Price. “[Ms. Denton] said we’d want to grow things like seaweed and kelp. Is kelp good?”

Denton allows that it’s okay while Philmon asserts, “It’s nasty.”

“We have to plant things that might not be part of our palette,” Denton says, explaining the importance of learning about food and growing environments in other cultures. Either shrimp or a variety of saltwater fish will be the marine culture, which is a bit trickier than freshwater. Fortunately, the school partners with the Henry Doorly Zoo, which Denton says is very understanding of a learning process that might result in the loss of a jellyfish or two.

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The first year, a class of about 19 students looked after the system. This year, Denton has 26 in her seventh-grade service learning class. Aquaponics is only part of the service learning class: This year, students will create lessons on video to show to other schools, ensuring that they exercise presentation skills alongside gardening and engineering and science. “The social aspect is really key as well,” Fripp says. “What we do every day is engage kids on so many levels.”

Another area of learning is in the art of giving. As part of her service-learning class, Denton and her students volunteer at Open Door Mission. When a food drive brought together a variety of canned and dry goods, some of her students asked, “Why can’t we donate fruit and lettuce?” Now, she and at least four kids take their aquaponics produce over to the mission after school every four to six weeks. “We’re able to harvest that quick,” Denton says. “And they immediately wash and serve it that night.”

Not exactly everything is donated. The students always eat a first harvest themselves, and they haven’t forgotten about the fish. A true aquaponics system is about raising fish to eat as well as produce, and Denton says her students decidedly do not view the tilapia as pets. “We haven’t eaten any yet,” she says, “but they keep asking for a fish fry.”