IME it has been a problem for the larger (adult) fish that suffer first if
the gases build up under a cover of ice, not the smaller ones (fry). I
allowed the pond to freeze over one real cold spell a few years back as my
bubbler was still humming and I thought it was running, but it had actually
broke, probably from back pressure as the air had no where to go. After it
stayed frozen over for a week, I got worried and broke open the ice - the
water had gone black and 4 or 5 of my largest fish floated to the surface -
lack of O2, I guess, but the youngest, smallest ones were still fine (for
how much longer, I don't know) I now don't allow it to completely ice over -
I check every morning and have to open a hole on the coldest days ( ~ -10 F
or lower) . It also might depend on your fish load to gallonage of water - I
have ~ 35 fish in 1100 gal pond, a bit smaller than yours, so maybe they
will fare better
Gale :~)
"elaine" wrote in message
ups.com...
We have a 15' x 21' x 3.5' pond, and temps here at the moment are -10c
to -25C (14F to -13F) with min 2' of snow in the yard(not drifts). We
always keep the "up pipe" from the fountain running all winter to keep
an open area but never heat and the goldfish seem to be fine lots of
fry overwinter and adults keep growing. We have had more than a few
-32C(-26F) days this winter so we had a HUGE ice volcano built up
around the end that kept trying to ice over despite our best efforts
to keep it open. Finally after a few -36C+(-33F) days it was finally
a balmy -28C( ) so we ventured out to see how the pond was doing.
Well it was ofcourse completely closed in;running but closed in. DH
tried to knock the top off again but only succeeded in knocking the
whole thing apart which then took the pipe to the bottom of the pond.
It was still running as you could see the ripples in the water but as
the hole was only 12" there was no way to locate exactly where the
pump/pipe was sitting. It has been -32C(-26F) with a few days of snow
and wind again so when I went out to check I can no longer see anykind
of open area, but pump is still drwing power so it IS still running,
and there is also a sump that pumps water from under the liner back
into the pond which is also still running(sort of). What I am wanting
your input on is whether I can let this go and have any fish survive
or whether I need to use an auger to keep an area open. I doubt DH
will go for the auger idea so I REALLY hope we can wait and see. I
know we will lose some if not all the fry if it is left but as the
adults seem to spawn nonstop all summer I can live with that. Thanks
for any input you gurus of pond land can give : )

Elaine