This 330w pond heater provides reassurance that your pond life will be safe this winter. The heater is thermostatically controlled and switches on automatically when frost is detected. The unit has been designed to cope with the harshest winters - even up to minus 30°C. The pond heater ensures oxygen has access to the pond and allows harmful gases to escape The resistance heating technology ensures a higher performance in the frost and protection against damage. It also maintains the warm temperature zones on the floor of the pond.