I have been dealing with hard crusty algae on the sides and bottom of our pool for some time now. I have been keeping the FC at 14-16 and PH at 7.2-7.4 for some time now, but it doesn't seem to be doing anything. All the other algae in the pool is gone now except for this crusty stuff. It is a light greenish yellow color, and the only way I have been able to remove it is to scrape it off with my finger nail. We even bought Scotch Brite pads, but they really don't remove it very easily either. Plus, I'm scared of them scratching the liner. Anyway, has anyone else dealt with algae like this? If so, what can I do to get rid of it?