I had some stains in my pool and someone on here said to apply a dichlor puck to the stain so I tried it and it worked great on most of the stains.
There are a few stains that it didn't work on. Small, circular dark stains. I'm going to try vitamin C on those and see what happens.
Anyway, it's an older pool and the plaster has always had dark splotches on it in places but I thought those were permanent but when I removed the puck from those small, circular stains, I noticed that the puck cleaned the plaster very nicely. I also noticed that the surface is much smoother as well as cleaner where the puck had been sitting.
I can't use pucks to clean all the splotches because it would take a year so any ideas on what I can do????
I'll see if I can post some pictures tomorrow.