-25C is about -13F. You must get great sun and be protected from the
wind. I've seen 4 foot high waterfalls freeze in temps that cold. How
does a small air bubbler keep the water from freezing?

Derek Broughton wrote in message ...
Gareee© wrote:

"Derek Broughton" wrote in message
...
MC wrote:

2) I've read bio filters are useless below 50 degree. So I won't run
it. Is it better to remove it from the pond, or just leave it? I
anticipate the heater will keep my pond around 40. I don't intend on
"heating" it, just keeping it from freezing solid.

40? _That_ is some amount of heat. If an aquarium heater works at all,
your surface temperature is going to be within a degree or two of the
freezing point. Forget the heater, use a bubbler.


How big a bubbler should we get for a 12x12 pond, 2-3 foot deep. We have a
number of small goldfish, but nothing bigger then 5 inches.

In S. Ontario, with temperatures down to -25C, I could keep a hole open with
a 15W aquarium air pump and one of the long (6") air stones, suspended
6-12" below the waterline.