Pond Boss Forums AERATION Systems questions Windmill or Electric?

Let me try to clarify as perhaps I have muddied the waters.

About Winterkill - you need to worry about this when you have a solid ice cover AND sunlight cannot reach the water - typically from snow cover but I supposed that really milky ice could also be a culprit. Cold water holds more oxygen and fish need less oxygen when cold, so if sunlight can get into a small part (1/3? 1/10? I think I have seen figures in that range) of the pond there should be enough O2 for the fish. If there is snow over ice, you can let the sunlight in by 1) aerating a hole in the ice or 2) snow removal over part of the pond. I believe guys like Wood way up North (Sometimes I think the only direction Wood can go is South) have to use snow removal - he gets multiple feet of ice.

About Supercooling - Water is the densest when it is 39 deg F (4 deg C), so in an undisturbed frozen pond, the water on the bottom will typically be 39 deg. The water just under the ice would be 32 deg. You get supercooling if you aerate a hole in the ice when the air temp is below freezing - this draws residual heat out of the pond and can lower the water temp from what it would be otherwise. Your bottom water can get colder than 39 deg F, which can stress fish that don't like cold water.

Is Supercooling real - yes, it can happen (or perhaps it would be better to say it does happen to some extent, possibly noticeable) if you aerate when the air temp is below freezing.

Is Supercooling a problem - depends on your situation. If you are trying to have Redears in Nebraska, a situation where Winter survival is on the hairy edge, I would say you have to worry about it. If you are raising cool/cold water fish (SMB, YPerch, Walleye) in MN, probably not a concern. BG and LMB in MN - perhaps you should watch out.

Aeration in Winter is not needed as often as in the heat of Summer. If you are watching out for Supercooling, you would want to limit your aeration time and do it when the air is relatively warmer. The Pros (as I remember) think that it is better to let the pond stay frozen over for up to a week than to over-aerate (and supercool) if the air is really cold. Unless you have an old pond with a heavy, decaying organic sediment load, noxious gases should not be a problem in this situation.

If I have confused you further I am sorry, and I guess we'll have to restart the Supercooling thread to get real experts involved. Whether you go with windmill or electric, supercooling can be avoided if you need to. I am sure the topic will be discussed more next Winter.

-Theo