DRS wrote:

I've had my pond for 7 years now (Nova Scotia) and all I do is take out
my circulating pump and use an air pump with the hose threaded through a
piece of styrofome. The hose drops about 18 inches in my pond, the air
bubbles keeps the water aerated, and keeps a hole open all winter long.
I've tried to use an air stone, but it wasn't as effective as just the
bare hose end. . If there is a large snowfall, I just shovel it off around
the hole so as to
be able to see the air bubbling through. Over the pump I just placed a
plastic coffee can so that the air intakes don't get plugged.

I was a little more careful with my air-pump in Ontario. It was fastened to
the inside of an upside-down plastic bucket, to keep it dry. I too found
that the airstone didn't work well - I lost two to the bottom of the pond.
I think the temperature fluctuations worked it loose too easily. The other
problem - less likely here in Nova Scotia - was moisture in the airline
freezing. Still, it's much less costly than running a heater or water pump
through the winter.
--
derek