Lately, when I open the pool (We have an auto-cover we keep on unless we're using the pool), I notice this "film" on the top of the water. It disappears quickly once the cover is opened and my thought is that it's simply "stagnant" water that is in contact with the cover at the surface. Since the cover is on, the top of the water just sits? No idea, but again - it clears in maybe 10-30 minutes with the filter running.
Thoughts? Not sure I ever had this before the cover, but we also got the cover late in the season, and this is our first year with the pool, so. . .
Latest chemistry below. Yes, FC is very low. Still trying to get the hang of setting the SWG properly with the cover. I also use the BBB method.
Also wondering if this has anything to do with the "scum" on the side of the pool ABOVE the water line. I can't even really call it scum. It's just a white film that does come off with some liberal Magic Eraser cleaning. Was going to do the vitamin C test, but haven't gotten to the store yet. The water fill was about 60% from a truck, and 40% from municpal water.
Water temp: 67*
Chemistry has been VERY stable (With the exception of the FC being low.) This is the first the pH has gotten this low and has been around 7.5 all season.
Last comment - whenever I test my water (TFT), when I do the CH testing, I always add five drops of the reagent first as I noticed the test "globs." I get a good result and use a speed stir, but still notice this when testing. So maybe it does have to do with metal?
See pictures. Thanks!