Why does my plaster turn blue in spots?

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,191
Tucson, AZ
:wave: Welcome to TFP!!!

Can you provide pictures of what you are talking about?

What chemicals have you added to your pool?
Any algaecides or #-in-1 tablets that contain copper?