I built a denitrification reactor to breed anaerobic bacteria and reduce nitrate. For this it is necessary to create a low-oxygen environment with a suitable environment for the growth of bacteria. This requires reducing the water flow to below 50 gallons per hour. I set up this small system using Seachem De*nitrate, two Fishes 150 reactors, a simple fountain pump rated at 63 GPH, a DC motor control circuit to control the pump speed, and a DC power supply. Plugging in was easy and it works like a champ!