Today I removed my SWG to check for calcium buildup (was pretty clean, even with 490 CH). The short time it was off, I could hear my whole system filling with air, meaning all the water in the system was draining back into the pool. Not really an issue, except for the fact that it pulled a bunch of DE powder from the filter with it. When I looked down at the bottom of the pool I could see where the DE powder was coming back into the the pool from the floor drains and skimmer.
So, am I missing a check valve to prevent this, or do I have to turn a valve to closed? My pool was a sparkling 61 degrees... and now its a little cloudy from the DE powder.