myLABSpool...Wow! 3 cents/kwh??? Could your electric provider come to TX???

But, to your point about heat loss at night...in the summer, I actually WANT to drop the temp in my pool so I log a lot of pump time in the middle of the night (unfortunately, no price break for nighttime hours here). Last year (first with the pool), we ran it 12 hours/day during the peak of summer, 11A-1P and 4P-8P and 12A-6A. My pool temp would drop from about 90-91 degrees down to 83-84 degrees by morning.

Right now, it's running for 8 hours, 11A-1P, 4P-8P, and 3A-5A.