Read this page: http://www.poolsolutions.com/gd/lowe...p-by-step.html

and, then lower your alkalinity to around 60 - 80 ppm, while holding the pH 7.0 - 7.2.

Continue to keep the chlorine at 5+ till all the green is gone. Brush the pool every few days. It may take 2 weeks or more to dissolve the calcium capsules, but you don't want to go faster, since really low pH can damage the fiberglass.