The Thermo Pond Perfect Climate Submersible Pond De-Icer is the first pond de-icer designed with all ponds in mind, both small and large. When used as a submersible, the Thermo Pond Perfect Climate Submersible Pond De-Icer is designed to keep open water in ponds up to 300 gallons, 18 inches deep or less. The de-icer is thermostatically controlled and all heating elements are enclosed so they will not harm or burn your pond liner. It also has inlets molded into the design so the heater can be used in tandem with air or water pumps to increase circulation. Thermo Pond Perfect Climate Submersible Pond De-Icer is not designed to be a submersible pond de-icer in ponds larger than 300 gallons. The best time to install your Thermo-Pond Perfect Climate Submersible Pond De-Icer is before your pond freezes over.