Hope this is in right area, but im wondering about my true gallons of water. My Liner schematic says 15,500, but if i use the pool calculator and put my dimmensions in, it comes out to about 24000. Wondering why such a difference? BTW, I have a 16x32. Shallow end is 3.5 for about 4 feet, then it goes to 8 on the deep end.