Actually, I should say the hatchery guy said that a relatively shallow 1/4 acre pond (9 feet depth) would not have a significant thermal layer - so mixing through aeration should not be an issue.
I wouldn't have any qualms turining hte diffuser in my trout pond as long as the air temp is above 39 F. At that temp there is no super cooling and the trout are more resistant to super cooling anyway.
Are you sure you want to see right after ice out? Sound like a good way to get them fungused up. I will be seining my trout pond, but will wait until the water gets into the 40's.
If you do seine in really cold water make sure you get them back on feed ASAP.
