Kahakai Elementary gets aquaponics system

Kahakai Elementary School physical education coach Janet Hunter has a new choice for kids who come up with at least one reason they avoid gardening.


Kahakai Elementary School physical education coach Janet Hunter has a new choice for kids who come up with at least one reason they avoid gardening.

“You don’t have to touch dirt to do gardening,” Hunter said. “No excuse.”

That’s because Hunter spent last week installing an aquaponics system at the school garden. The system includes a tilapia tank, two vertical filters, a plant bed with charcoal and dirt to continue filtering the water and three water troughs in which lettuce, tomatoes and other plants will grow. The tilapia’s excrement infuses the water with nutrients that feed the produce, Hunter said.

The resulting lettuce tastes better than conventionally grown versions, Hunter said.

Kahakai came by the system — which would cost about $5,000 if purchased — a bit serendipitously. Cecilia Viljoen, a marine biologist who is the research and development and nursery director at Big Island Abalone, put the system together several years ago for personal use. She fixed up several old tanks from her employer to create the system. When Viljoen moved after growing lettuce with it for two years, she took it to Nursery Solutions, where the owners used it for a few more years.

That company decided recently to do some property improvements and needed to get rid of the aquaponics system, so Viljoen offered it to a few schools. Hunter saw the offer and responded quickly.

The donation came like so many others to the school, she said, just another example of how Hawaii residents pitch in to help keiki.

Students and the school’s gardeners haven’t had the best of luck growing lettuce in the plot on school property, Hunter said. The heat and salty soil inhibit growth. The students who had learned about the aquaponics system, which Hunter spent about eight hours on Sunday installing, were excited.

“They are so jazzed,” she said. “They know it’s the cutting edge. They’re excited to be one of the schools, if not the only elementary school, to have this system.”

Viljoen said she was happy to help students.

“I’m happy to train them and get them going,” she said, adding that children seem to be naturally drawn to watching an aquaponics system.

From seed to a full head of lettuce usually took six to seven weeks, she said.

The tilapia will reproduce and provide additional fish to perpetuate the self-contained system, Hunter said. Right now, the largest of the fish — the oldest of which are a few years old — is about 18 inches long. Eventually, the school may even be able to sell the tilapia.

Hunter said the first students to learn how to use the system will be ones enrolled in a summer program that begins in June. That gives teachers a smaller group to work with as they learn about the system themselves.


Even teachers were making their way across campus to catch a glimpse of the tanks, filters and water beds.

“The adults are pumped up about it, which pumps up the kids,” Hunter said. “It’s neat to be part of the process.”