We've been loosing about 200 gallons of water daily. I fill the water about 1/3 up the tiles, mark the level with a piece of blue tape. Over nite the water level drops to just about the bottom of the tiles. I've blocked the skimmer line, the 2 return lines, so the lines are all sealed. I've used Waterweld around the pool light to seal it.
There are a few places where the tile grout is missing, particularly near the skimmer. I'm about to call and get some estimates to replace the tile grout.