Organic staining should eventually lighten and go away with a slightly elevated FC level. Refer to the
FC/CYA Levels to ensure your are first in the appropriate (ideal) FC zone, then consider raising it by an additional 3-4 ppm for a few days. If the stains still don't go away, consider rubbing a stain with a chlorine tab or sprinkle some cal-hypo granules on it as a test just to ensure it is indeed organic.