We purchased a home with a pool about a month ago. Our pool is a 12,000 gallon salt water pool with a spa attached. We have to add water to the pool daily. It is dropping 2-3 inches each night. We are trying to figure out what the problem could be before the Leak Detect company comes out in a few weeks and charges us $425 just to find the leak. This is what we have noticed. The water does not drop much throughout the day but when the pumps/filter run at night is when the water drops. Today my husband tried turning off the skimmer and just leaving the main drain and pool return on to see if we could narrow anything down. When we returned home about an hour after the pumps kicked on the pool water had risen and the spa was almost completely emptied. Does this mean anything or was this just us not knowing how run our valves. Does anyone have any ideas or advice on what we are doing wrong or how we might be able to find out if there is a leak? Please Help!