THanks for the tips. Unfortunately, I tried that in some areas. Since this was the second plaster job in two months and he used a new plaster crew because I think the other crew got canned fromt he first debacel we went threw, I trust the builder when he says that is normal. I did the vitamin C trick, chlorine tab and nothing. A steel bristled brush did nothing to these areas.. Fortunately its not overcast too often down here in TX so I dont have to see them. And I got an extra year warranty for the plaster so I know the pool company wasnt screwing around with this.