Hello, My parents have 11 ducks, Mandarins and Call ducks. They live in MA and they have a small kiddie pool to swim in. It's one of the tiny ones probably three feet across maybe 3 1/2. Anyway, winter is here and it is freezing the water in the pool. Is there a small de-icer that they can use to keep the water unfrozen for the ducks? I don't want to burn a hole in the pool or burn the ducks. I know about de-icers because I have one in my trough for my horses. This is their first year with so many ducks. In the past they only had 1-3 and they only gave them a small container of water to bathe in etc. Thanks!