Groan! Didn't keep up with my chlorine (or chlorine adding)testing for the last few weeks. Since the water has been clear and below 60 degrees I didn't think I would have a problem. But I come home yesterday and find a bright yellow ring around the waterline of the pool! It can't be pollen, there is nothing in bloom right now! Is it the dreaded mustard algae? I'll try and get a picture when the rain slacks off. Water is still quite clear. Going to test right now!