For ponds up to 1000 gallons. The world-foots most energy efficient pond heater. Thermo-Pond is a unique patented pond heater that keeps a hole through the ice in backyard ponds for just pennies a day. In fact, Thermo-Pond can save up to $30.00 a month in electricity VS. those high wattage stock tank style de-icers. Just think, Thermo-Pond pays for itself in as little as 2 months. Thermo-Pond floats on top of the water and is thermostatically controlled to never get hot.