We had our first above ground pool installed by a local dealer this spring. A 24ft Doughboy with a Poweline XP 1.5 HP Pump and ECO Cartridge Filter. When I try to clean out the filter basket on the pump the water flow does not stop. Per our dealer I should be able to turn off the pump, plug up the skimmer and no water should flow from the filter to the pump. That's definitely not the case. The water is flowing from the filter to the pump. Should the dealer have installed a check or a stop valve to prevent this. The dealer is not being very helpful and pleading stupidity.