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  1. R

    Tiny Brown spots - not black algae or rust?

    I have been lurking around here for 4 yrs and love this site. Sadly, I have an unusually difficult one to post. 6 mos ago I discovered brown/black "spots" on the pool steps and certain areas on the floor. About the size of a pin head or a bit larger (irregular shape). Scraping with a thumb...