I keep my cya close to 50 even though they say I should run it higher. When the algae appeared though I was closer to 25 due to a drain and fill. I never let the chlorine go below 2 ppm. It doesnt seem to matter where I keep the chlorine this stuff always reappears. I am just curious if this is a regional pollen problem or not. I am very good at keeping up with pool maintenance and a friend down the road always gets it the same time I do.