Cecil,
I believe you helped us out 5 years ago when we went through our last rainbow stock program. If you remember, we had a previous stock cycle that didn't make it through the first summer due to the water temp getting too high. Subsequebnt to that failure and learning experience we did several things:
1.) Dredged out the pond to 10-12' in depth along one length where is previously was 3-5' deep. the other side is still shallow at 3-4'
2.) added a supplemental well that we constantly ran in addition to the free-flowing artesian well.
3.) Controlled the aerator based on air temp! Yes we found a method to turn on the aerators (2) only when the air temp was 60 or below. Agitating the water helped tremendously in lowing the water temp during the cool nights in northern Michigan (typically get into the 50's at night) When the air temp got above 60 we would shut them off and we were able to keep the water heavily oxygenated as well with this duty cycle. There were a few days during the heat of the summer where we approached 66 or so in water temp yet the fish went deep and survived for a good life cycle of 5 years. We may have lost a few during the heat of the summer yet it wasn't more than a few that we counted so we skirted by this issue that got us in the first place. We also could reverse this approach and heat up the water if we needed to by a few degrees.

1/2 acre pond in West Branch, MI. Plan to stock in early 2025