What valves do you leave open when cleaning pool?

You should have two valves: one for the skimmers and another for the bottom drain. Close the valve to the bottom drain. One of your skimmers should have a rotating disc which will cover the intake at the bottom of the skimmer intake hole. Rotate the disc. In this manner all the suction from the pool pump will be at the one remaining skimmer. Attach your cleaning hose to this remaining skimmer while vacuuming the pool.