After eyeballing and using a string to the level the ground last year (which after we filled the pool we found we were way off.) Yesterday we bought a zircon water level per the advice of Billy for about 25 bucks. We then made two markings on 12 18" stakes, at the same place on each stake. we started at the lowest point of the ground (well actually we started at what we thought was the lowest point only to find after using the water level it wasn't the lowest point so then we had to start over at the lowest point) then hammered the remaining 11 stakes in the area about a foot wider then the pool. On each stake we marked where it was level with the lowest point. Then measured the distance from the level line to the pre makred line which told us how far down we had to dig to make the ground level. The water level was so easy (the moving the dirt to make the ground level was an all day event...but now its done.) thanks Billy