Pool Maintenance?

We purchased a house with an in-ground pool. We had a large hole in the light niche fixed, but we are still seeing some water loss. What can be expected as far as normal evaporation? This is a 19000 gallon round pool, and the temps have been in the mid 80s. We lost 1/2 inch in two days.

Also, I found a product online that when poured into the pool, can fix cracks up to 1/8 inch in the vinyl or plumbing. Does this really work without clogging up the filtering system?

By Dana Poston from Northern VA