Just had my DE filter replaced with a cartridge filter. The pipes going to the motor have three valves. Since the replacement I am losing water and can't remember which of the valves should be open and which should be closed. I believe one is for the vacuum system which I don't need, one is for the skimmer, and one for the main drain (can't remember which is which though). The two valves on the right regulate whether I am using the returns or the in-ground cleaning system. I have no problem with that.