I had my pool plastered (gem coat by Florida Stucco) on Friday. We filled it with city drinking water from noon on Friday until Saturday morning. The PB said to add chlorine right away, but the start up procedure I found on here said to wait 72 hrs. I did not add chlorine. Well, Sunday we already had yellow algea growing in some spots and black spots started developing. This was despite my brushing and following the other directions. It will be 72 hours tomorrow, so I'll start adding it and the CYA. Anything special I should do?