I have been in the pool retail business for quite a while and I had a customer ask me a question the other that I wasnt quite sure how to answer as we do not have many ingrounds around here, and mine is fiberglass and concrete. He was telling me that he has a plaster pool with gunite underneath. It is indoor. He was getting what sounded to me like algae, but when he brushed the pool walls, white dust was coming up from the plaster. Is this a normal reaction? The pool is only a few years old, and he swears to me that his water is well in balance (because I suspected etching). Could anyone tell me a bit more about plaster pools?