I have a Sharkline above ground pool 18X33 and about 15,700 galllons. I recently added a Hayward propane heater and 500 gallon tank. A few days ago I fired up the heater and raised the water temperature to 85 degrees. The water level was quite high due to some recent rain (top of the skimmer). I keep a solar blanket on the pool when we are not using it. Yesterday we used the pool, noticed the water level was a little low and ran the hose for several hours while we were in the pool. Today the water level is down 2-3 inches again. Is this normal evaporation or do I have a leak? This would be the second one and the pool and liner is only a few years old. I had an Armor Shield Floor Pad installed with the pool. Upon inspection around the pool I did not find any moisture or water.