My Northern California Koi breeder buddy that lives in the foothills, is keeping his fish warm all winter with one of my cold temperature breeder heater aquaculture / aquaponic heat pumps. The Koi are healthy and eating like crazy. No dormant sad, bottom dwelling fish here. Even though there is snow on the ground, the heat pump is keeping his pond warm. It will keep heating down into the high 30’s Fahrenheit or about 2 to 4 Celsius outside temperature. He is spending about 1/6th of what he would pay for a electric element or propane (LP) heater to operate and his fish don’t go dormant in the winter and not grow. Also in the summer it will chill the water so that the fish won’t get stressed by water that is too warm. So come on all you hydroponic / aquaponic type people out there. Make this a year of happy fish and plants. I know that if they could talk, that they would thank you. If you get a aquaculture heat pump, It would make the little creatures and me happy too, and I will thank you. 🙂
Stay warm and safe out there.