I've seen this stated a few times in this thread and I don't think email@example.com said:That is the essential energy difference. Now let's say
that the ambient air is 80F and the pool water is also 80F.
true. The pool temperature is going to be the average of daytime and
nighttime temperature plus the effect of evaporative cooling at the
water surface, plus the effect of cooling due to ground temperature.
All and all, I'd expect the pool water during the time the AC is in use
to be significantly lower than the air temperature.
Before I had my heater, with air temps in the upper 90s I'd still have
the water at 80 or so. If I remember right, 82 was an all time high.
The heating from the AC system heat exchanger isn't going to make much
of a difference for pool temperature but the AC system will cool better.