The Thermo-pond is a unique floating pond heater that keeps a hole free allowing toxic gases to escape all winter long. Thermo-pond is thermostatically controlled and operates on only 100 watts that's 12-15 times less than other leading brands. Your fish and your pocketbook can't live without it! * Heater will not harm pond liners or plastic ponds * Tested to temperatures past 30 degrees below zero * Save up to $60 in energy costs.