I was wondering if someone could explain to me just how I would go about draining water from my pool if I needed to replace water. I have a cartridge filter setup and therefore, there exists a little hosebib type spigot on top of the pump. I understand that the pump would need to be on in order to drain via the spigot. My question though really deals with how to go about it as once the water level drops below the skimmers, I would be sucking air. Am I to close the skimmer valves and the cleaner valve and open only to the bottom of the pool drain?