US: Students combine greenhouse and fish nursery
After learning about an internet auction from a Kansas City magnet high school's FFA program, they were able to purchase the basics for the system. "We bought all these tanks and most of these pipes for $25," Kiehl said, adding though, the final costs including pumps, was a lot more. "We went up and got two goosenecks of stuff and brought it home."
The system includes four 400-gallon tanks, two flat flood tables for watering standard greenhouse plants and baskets, along with hundreds of feet of water and air lines. Last week they added about 300 goldfish, fantails, Koi and other ornamental fish.
"We're going to raise them up and hopefully at the end of this year, when we have our plant sale, we'll sell them for water gardens or we'll sell them for fish bait," Kiehl said. They expect the Koi to grow about two inches longer in that time, while the goldfish should grow up to 1.5 inches longer.
But besides the fish, the project also includes using the fish water and its natural fertilizer to raise their traditional greenhouse plants.
"It's supposed to be 10 times better as far as nutrients for the plant," Kiehl explained. The system he designed and built with the help of other FFA members uses a large pipe in the center of the tanks which accumulates the solid fish waste.
"The idea is to take it over to that flood bed over there and the plants suck it up and clean the water out and we repump the water back," he explained. "That's how we clean it and feed plants at the same time."
By using a biological filter and adding beneficial bacteria weekly, the ammonia from the used fish water is converted into available nitrogen for the plants.
"Instead of watering from the top, we are watering from the bottom," explained FFA advisor Terry Jenkins, exhibiting the extreme difference in root systems and color between greenhouse plants fed by commercial fertilizer and those watered from recycled fish water. "They are healthy, but nothing like these that we've ran through the fish tank."
They also will be growing lettuce in the water, and have built containers out of piping to keep the plants floating in the middle of the tanks. The Kansas City school sells more than 30,000 heads of lettuce a year, Kiehl said, adding the KC system is much bigger and more elaborate.
"The difference between fish waste and animal waste, is there is no ecoli," Jenkins said. "You can take it right out of there and it's not an issue."
In order to keep the fish healthy, the students in the Ag Science 2 and Greenhouse classes are in charge of monitoring the system including pH and nitrate levels, as well as water temperature.
The original plan was to raise game fish such as crappie, tilapia or bass, but the water temperature would need to be more constant, making it too costly.
Jenkins hopes the project will help teach the FFA students skills they can use later in life.
source: marshallnews.com