It is unlikely that the conclusion I should draw out of this is that to have a successful trout pond, I MUST have new cold water going into the pond to ~ cycle out the old water in the pond daily.
At least one very knowledgeable trout farmer here runs ONLY fountains/surface aerators and does not recommend diffused aeration; now I'm not suggesting I agree or disagree with this recommendation but he does successfully raise a large quantity of trout and isn't destratifying the water column and his trout aren't dying because of lack of oxygen in the summer in the cold bottom layers.
I'm guessing there is some appropriate answer between the extremes that will result in a deep pond maintaining cold water at the bottom that trout will survive in.
