My small (approx. 5K gal.) IG fiberglass pool is losing water at a rate of about 4" in 24 hours. A leak detection company check the pool and all the lines and the only leak found was behind the light. A company came out and replaced the light (which needed replacing) and used a marine grade epoxy to seal the leak. It is no longer leaking according to a dye test. The pool is still losing water--regardless if the pump is on or off. Can the issue be at pump or filter? (I don't see standing water there. It is usually a little damp but that can easily be the sprinklers and shade.) I read that sometimes the backwash line can be leaking even when the pump is on filter. Is that a possibility? We don't have to hook up a backwash hose as it is piped. I don't know where it goes as we are just renting the house. However, there is a spot in the yard about 30 yards from the pump that is always very wet. We are completely perplexed here. Any ideas what could be causing it? I appreciate any help!