Because I live in the Deep South, I do not have to bother about a frost line because aside from some chilly weather occasionally, we don't have to deal with frozen ponds. But those of you who do, need to know what the frost line is in your area. You can find out by calling your local extension office if you don't already know. Oh, the frost line is the depth of soil where it no longer freezes. For some of you, that is really deep. When you are building your pond, know your frost line and dig the pond deeper than that. That way, your pond will never freeze solid. Your fish have a chance of survival even if the top of the pond freezes over. I do advocate keeping a hole in the ice, but sometimes that is not possible. Fish are in torpor, a form of fish hibernation all winter, so they just lie around at the bottom of the water in suspended animation, if you will.
Digging below the frost line will mean less chance of damage to your liner as well. You have, of course, removed all your pond equipment already and stored them safely. Right?
