That is interesting John.There is one thing I just thought of that might be the source and that would be the salt I added to the pool. I will have to go to home depot where I purchased it and see what other chemicals they may add to the salt.
Now as for it coming from the plaster itself. Is there a way to tell if this is true? Are there tell tail signs? Also should I be concerned with my CH at 550 if it stays there and does not continue to rise? Thanks for your information.