We're noticing that when we have the skimmer turned on, we're getting air bubbles in only one of the 2 jets. If we turn on just the main drain, we get no air bubbles. Also, our skimmer does not have a door (weir?). Should it? I also noticed there's a vortex in the skimmer when I lift the lid. Is not having a door causing an air issue? My husband didn't see any holes or mounts for a weir so I'm thinking it never had one. We just moved in a few weeks ago so we're still learning. Maybe our water is too low?