I just built a used Kayak pool this weekend. Its about 20 yrs old I think. I bought new walls, floor drain, gaskets for skimmer/retur and a liner. Everything seemed to go OK and the pool went up without issues (after a LOT of work). I have a Hayward SP0735 4-way ball valve that connects the skimmer and bottom drain to the pump/filter. I have the ball valve set to closed but water is still coming out of the floor drain and into the filter while filling the pool. The pool is about 1/2 full now. The drain pipe sits below the water level so obviously gravity plays a part here but I would expect that when I close the valve, there should be no flow coming from the drain. Is it safe to assume I have a faulty ball valve or is it some kind of issue with the ball valve not withstanding the pressure from the water trying to gravity feed into the filter?