I'm not an aeration officianado, but if you do not aerate from the deepest point in the pond, that water will become anoxic and totally devoid of oxygen.
I would place the diffusers in the deepest part and run them nightly as trout require very high dissolved oxygen levels and that will allow them to survive temporarily higher temps...lower temps with lower oxygen will result in a quicker kill.
Perhaps one or more aeration experts can weigh in on this thread and offer real world experience here.
