Friday, February 14, 2014


photo credit:

Aquaponics combines the technologies of aquaculture (fish farming) and hydroponics (growing plants in water) in one closed loop system that harnesses the benefits of both. The poopy water from the fish tank is converted into nutrient rich water to feed the plants, the plants filter the water and the clean water is sent back to the fish. Ta-da!

We had the opportunity to see a small scale aquaponics in action.

David of Canadian Aquaponics is a mechanical engineer and built his experimental aquaponics system in a small warehouse.

The tank of tilapia got quite excited at feeding time. David showed us how the fishy water got siphoned down to feed his lettuce and basil. The kids were able to harvest some lettuce and we had a tasty sample of fresh organic salad right on the spot!

David explained to us the nitrogen cycle that turns ammonia in the fishy water into nitrate that the plants can then absorb. The kids learned to test the pH, ammonia, nitrite, and nitrate levels of the water.

David also explained the importance of using siphon to move the water through the tiers between the fish tank and the plants in his aquaponics system.

I think he lost some of us when he described the bell siphon to us. We had to do some digging when we got home. Thankfully we found a good video explanation online: bell siphon explained. We also learned that the toilet is a siphon! (Check out the video "How Does a Toilet Flush?" on Discovery Education Canada.)

Serena's understanding of air pressure through her weather unit study came in handy as she grasped the new concept of siphoning. She was eager to practice her new found knowledge with a few simple experiments in the kitchen:

She went siphon-crazy and showed Daddy how to siphon grape juice into her glass at dinner time. Who needs to pour when you can siphon!


  1. We did video it explained it very well .Thank You
    Love Nanny & Papa

  2. Very well presented Serena! You are a great scientist!!