I am doing my first drain, clean, and refill of a tub I bought refurbished 4 months ago. I noticed before draining a white film around the edges near the water line and figured I could clean it when I drained. But this stuff will not budge despite my scrubbing. Is this "scale"? It seems more like discoloration than actual substance. Any advice on how to remove it? I know there are products for prevention of scale, but not finding anything for removal.
