I'm not putting them back in for the last few days before closing (long story), but noticed that the CH should be brought up a bit. I know it always causes lots of foam in the pool shortly after adding it, but then subsides. Any difference without having the grids in? Can't see that it'd do any harm (?) These last few days I'm basically just circulating water. I usually do have the grids in right up until the end but things didn't work out that way this season.