Originally Posted by
mplskoi
One minor disagreement with that thinking- very cold air generally has very low humidity while warm air usually has high/higher humidity. So, when it comes to aerating your pond, pushing cold air with low humidity, because it has very very low mass will not impact your water temp much at all. While (at least theoretically) pushing warm moist air will have a greater impact. So in the experiment that OP did he warmed very dry air up, but because of the very low mass of warm dry air it would have little impact.
Rick, I liked your analogy of sticking your hand in a hot oven compared to into hot water.
Regarding keeping any pond warmer during the winter I think that energy conservation is money more well spent than any form of heating. As of Feb 8 my pond, here in Minnesota, is still at 43 degrees F. With no heat added whatsoever. We have had a somewhat mild winter by historic norms, but we have had I think 7 nights with subzero temps.
I am dreaming up a pond rebuild for next year that will be insulated to a point where I can keep the water close to 55 with very little heat added. This will require that my filter pit be as well insulated as the entire pond with no water lines exposed to outside of the insulated zone.