Other than a 1500 watt stock heater, which would get very expensive, what can be done about freezing stock tanks, i have one of them and a kiddie pool for my birds, i was wondering about some sort of recirculating pump, or an aerator? We certainly get below zero here but I would say the average is 15-20 degrees during the day at worst. Somewhere I saw some kind of heated recirculating pump device but i cant find it now., any suggestions?