This may sounds like a dumb question, forgive me. Is a diffuser/aerator necessary in a pond?
I'm not sure it is required in our part of the country as the lakes modify temperatures, and wind keep a strong thermocline from forming except on the hottest days. I seem to get decent mixing without the aeration mixing, and my pond is 15 feet at its deepest.
It may become necessary to add aeration as the pond ages if you wish to keep organic build-up to a minimum, but for the first several years you can get away without it. Just keep any large trees far away from the pond as to prevent leaves from blowing in, and that time can be extended.
Some here require aeration as they are pushing the boundaries of what their water will support by regular feeding, fertilization, and an amazing thriving fishery. That organic load can use up O2 quickly in some circumstances, and aeration allows success.
As for ice, I prefer to plow it off and let sunlight through to make the O2, and skate on it for fun. An aerator just blows a hole in your hockey rink. Skating is a great reason to keep your pond round/oval instead of kidney-shaped. Know anyone who plays hockey?
Nobody around me has 24/7 aeration, not a single person and there are a lot of ponds. A few have the windmills, but they don't seem to run when you need them the most, like when the pond is locked in ice and under a thick blanket of snow, or when we are in an extended hot spell.
To each their own though, and a lot depends on your goals, and how much you consider a fish kill a serious problem when something goes wrong. Things WILL go wrong, aeration reduces the chances.
