Does Water from swimming pool evaporate at a faster rate on cool nights?

The rate at which your pool evaporates depends on a combination of the temperature the wind and relative humidity Tis can be between 12 to 25 mm per day. If you feel that you may have a leak some where The thing to do is put water in a water bucket then Mark the water level on it. put a discreet mark on the pools water level and leave it for between 1 and 2 weeks. if the water level of the pool has gone down considerably more than the level in the bucket you probably have a leak somewhere.

PS if you can hang the bucket in the pool to keep it at the same temperature all the better