I am currently servicing an above ground pool that is 30 x 15 with a pitched liner that goes to 6 feet on one end. The pool is about 17k gallons. The pool is on the down side of the a mountain. There is a retaining wall build below it and it sits obviously on the level part. The thing it it has 2 skimmers, 2 returns and a center drain. The guy is currently using an above ground 3/4 hp pump and no getting much movement of the water. Am I correct in thinking because this is on the side of a mountain he would need a self priming inground pump of at least 1 hp?? He just bought this and put it on before he hired me. He got sick and can't maintain it but I have never seen a set up like this.