The NEW Aquascape stainless steel Pond De-Icer is ideal for keeping a small hole opening the ice during cold winter months, and insures proper gas exchange helping keep your fish alive during the winter. It is important to leave a small hole open at the surface of the pond allowing for necessary gas exchange. This will allow the toxic gases to escape. In extreme conditions or gardening zones above USDA zone 5 we recommend the de-icer be used in conjunction with an Aquascape pond aerator. ? Keeps a small hole in the ice during winter months ? Helps increase pond oxygen levels ? Durable stainless steel construction prevents corrosion and cracking, unlike plastic or PVC types. ? Integrated thermostat saves you electricity ? Built-in LED light indicates when heater is in use ? Built-in LED light indicates when the heater is in use by iluminating RED. ? Built-in LED light indicates when the heater is plugged in and not heating by i