A quote from Ben:

(Get) your pH between 7.2 and 7.8, your alkalinity below 140ppm, and know what your stabilizer is, use the "Best Guess" chart... to determine the CORRECT chlorine levels for your pool.

Once you've done all that, adjust chlorine to shock levels AND use your brush. Continue doing so (chlorine AND brushing) for 1 week AFTER all visible algae is gone.

Then, make sure you MAINTAIN adequate chlorine levels for your stabilizer level.

Meanwhile, if you can get some calcium hypochlorite shock, and then BRUSH the spots, followed by sprinkling them with cal hypo, that will help.