Do I really have a leak, or is it the result of weather conditions, splashing, back-washing?
In the Midwestern part of the U.S., evaporation, impacted by water temperature and wind speed, can account for up to 1/4" a day of water loss from your pool. See below for a simple test that you can do to either confirm or eliminate the possibility of evaporation.
Heavy use with splashing and much entering and exiting of the pool could be another reason for water loss.
Pool cleaning performed by "vacuuming to waste," or excessive "back-washing," will also add up to what would appear to be a leak.