I have just cleaned my pool to get ready to paint for this year. I have a fiber glass sides and the slopes and bottom is treated concrete. We had the pool put in 1988 and never had to have anything extra special done. The calculm has build up on the sides and bottom so we empty it. The pool is 22' by 40' and 10' at the deep end. Our problem is we don't know what to chalk the corners and the parts where the fiber glass meets. It has a type of white chalk in it now, but some of it is coming out. Any help would be appreciated.