Heated Electric Pond Koi Fish Stock Heater Convertible De-icer Ice Chaser H418c This de-icer will keep your tank from freezing in the winter and works best in tanks of 70 to 200 gallons Versatile design which allows this stock tank heater to be used as a floating or submersible device Thermostatically controlled to turn on and off automatically The cord is protected by a metal spring which serves to deter chewing The patented cast aluminum design is safe, reliable, and efficient