We've had this problem for a while now and wonder if other folks have seen it, too. Our pool was new last summer and at one point very early on, FC hit zero for a couple of weeks. At first sign of cloudiness we got professional help and also started our education in pool chemistry. The treatment was super chlorination and the pool was back to sparkling soon enough.
However, all is not perfect. Every time we open the auto cover, there is a thin film on the water's surface. Not over the whole pool, but mostly it is heaviest near the edge where the cover rolls up. It's an oily looking film that sometimes has white flecks in it. If the pool is in direct sunlight, the film will clear in an hour or so. Aside from the film, the water is sparkling.
One observation is that once the pool is uncovered and open long enough to clear the film, closing and opening the cover results in more film. This leads me to believe that whatever I'm dealing with is on the underside of the auto cover. There also seems to be a correlation with the water temperature - the warmer the water, the more film on cover open.
I've tried scrubbing the underside of the cover with bleach from within the pool. That was a nasty bit of work that didn't clear things up. It may have lessened the amount of film initially, but it's back to where it was pre-scrub.
So, anyone have experience with this? I'd love to know what I'm dealing with. I'd love to know how to treat it. And in the meantime, is it safe to swim?
FC=3; TC=3; CC=0
Water temp = between 70* and 80*