Last spring when I removed my winter cover I notice that my water level as extremely low, ay more than previous years. Even though I as surprised I didn't think much of it. Once I started to go through the process of opening my pool and filling the pool to the required level (note it was still early spring and still rather cool), each day I notice I was loosing more than a 1/2 inch of each day, it could of been 1 inch per day, again confused on why as I never had this issue. So I started to mark the water levels and keeping a eye on it. Neverless it keep loosing water so one day I just stop putting water in to see how low it would actually go. Weeks past and the air and water temp started to warm up and the pool level seem to finally stop at some point. So I filled the pool back to the required level and it pretty much stated there throughout the summer. Once we hit the end of summer and the air temps started to drop I notice that the water level start to drop just like it did in the early spring. I seemed to me that I only lost large amounts of water only when the air or water temps cooled. As in spring and now, I looked for any visible signs of water around the entire pool perimeter and could never find anything. I mean come on if I was loosing a foot + of water over a course of a few days you would think I would find it, but never did. Right now my pool is about 1 foot below the return and I have not put water in for a few weeks. Looking for recommendations on what to do. Note the pool is only 3 or 4 years old.