First year with our partial inground/above ground pool. It is a Evolution 18' 52" round pool. We believe we have a leak. We filled the water to the Max on the skimmer line yesterday evening and by morning it is down to the minimum line on the skimmer. That is a 2 inch drop overnight. The pool is covered by a solar blanket and a heavy duty tarp. The outside temp dropped to about 11C, heater was set at 28C. How do we find the leak if it is one?