Stop your pond from freezing over in the winter. Float this polystyrene ring on your pond and attach a hose from your air pump (sold separately) the air will be forced down into the pond and bubble back up dragging some warmer water with it. This should keep an area of your pond from freezing in all but the worst of wintry conditions. It is essential to keep an area ice free for the safety of your fish.
Hozelock Ice Preventer - B00CZCJIGI