Mike W. Suggested in a different thread that he had reduced his run time to start up around 11 pm instead of 9. This should allow some of that hot upper water to cool off some before being turned in. This is worth a shot IF you are comfortable they your pond is getting enough turnovers per day.
I try to not run the air during the heat of the summer when the ambient air temps are warmer than my pond...9am in your parts may get that way.
