I'm losing an inch of water a day it seems. I checked where the backwash water comes out and the pipe is full and slowly water is coming out while in filter mode. I have a Pentair sm10-3 multivalve (side mount) and my best guess is to replace the spider gasket. Does that sound right? Anything I should know beforehand? I watched a video of someone replacing a gasket and they put some sort of sealant on it - should I do that? If so what kind? Should I just close the pool (getting close to time anyway) and replace the gasket in the spring?