Pottsy in Ottawa:
Currently, it is 95 degrees, with 70 percent humidity, here in the Texas Hill Country. So far be it for me to give advice to a Maple Leaf on how to keep water ice-free in the winter.
I might, however, direct you to one of the long-time Pond Boss supporters, Malibu Water Resources in California. The question for those folks is straight-forward:
On a pond here in glacier country, will your windmill aerators keep a 5' x 5' area free of ice?
Mark McDonald
Editor, Pond Boss