The purpose of using this heater is to create a ice-free area around the unit. Without this, ice on the pond surface will seal the pond resulting in a build-up of poisonous gases in the pond which will kill your fish. The pond heater is designed for safe and continuous use with the following features: robust aluminium cylinder which allows all-round heat distribution, a reinforced plastic casing to prevent thermal and mechanical shocks, making it virtually unbreakable. The heater is set onto a durable plastic floating disc and comes with 10 metre outdoor cable on the top There is areas designed for birds to bathe and drink.