kathy wrote:
Hmmmm...
I don't think we've ever addressed the size of the
hole to be kept open in the ice that I remember.

If you are concerned you can add an air pump and
bubbler and that will increase the size of the hole
as that worked for me during an especially bad
winter (for us).

kathy


My feeling is that if you've got a good vigorous bubble-stream going,
the size of the hole isn't critical: the gas exchange will be driven
more by the bubbling than the exposed surface area. It probably even
gives you some lee-way if the hole freezes over completely: if air is
going in, it *must* be coming out, and presumably exchanging oxygen for
waste gasses along the way. Not that you shouldn't re-open it, but you
probably don't need to panic and rush out in your PJs at 3AM in
mid-January, either ;-).

-- Kizhe