I had the same thought abouthe air temperature.
Letting the water evaporate from the pool surface might be more effective at cooling the pool. Plus, what is the temperature of the incoming water that you are using to replace the evaporated water? That is probably going to have the biggest effect of any of the variables being discussed.
NAR# 92125 L1
Total Impulse for 2011: 1,729 N/s
Total Impulse for 2012: 1,689 N/s
Total Impulse for 2013: 911 N/s
A:13, B:5, C:21 D:2-20, E:4 F:0, G:0, H:1, I:0