I opened my vinyl IG pool last week, and have noticed that I lose about 1/2" of water per day. I have a slight drip at the pump, at a rate of 15 drips per minute, which according to a water loss calculator that I found online, amounts to about a gallon during a 12 hour run. That certainly does not explain a 1/2" of water in a 24k gal pool. I can't find any cracks or holes in the vinyl, I tried food coloring around some suspect areas to no avail. This is not due to evaporation. The temperature has been in the low 70's since I opened the pool, and I didn't even lost 1/2" a day last summer during 100F days.
I'm not sure if you guys can help me since I'm sure that's a tough problem to solve without seeing the pool, but maybe you can point me to common problem areas.