Hi! I don’t know where exactly to post this. But after it rains we get these oil slicks of microscopic black things. I can’t tell if they are alive or dead - last summer I thought they were alive but today they don’t seem to move. Maybe because I’m slamming. Anyway, anyone have any clue what these are or how to prevent them or get rid of them? They are so gross and sit on the surface of the water which makes them hard to skim - they don’t ever get to the filter. This year I’m trying a filter sock but it’s still a mess. I don’t want to swim with these in there.