I am trying to set up my 40ft. above-ground pool but one end is consistantly lower than the other. The string level and others that we have tried show the ground to be level, yet when we start to fill the pool, all the water runs to one end. I checked out the fix-it forum and I liked the idea of using a pivoting board but how can I use that to measure all 40 ft (15 ft. across)? Do I start from the middle, level where needed, and then move the board down to the next section? Any help/advice would be greatly appreciated. Summers here are VERY hot!!!