I have a saltwater pool with a river rock finish and glazed iridescent tiles at the water line. I am having trouble finding a cleaner that takes off the hazy water scale buildup that doesn't take off the iridescent finish as well. Has anyone had any success or issue with this? I tried to attach pics of what the tile should look like, what the tile looks like, and what happened when my pool guy tried a product that ate off the glazing, but it would only let me upload one so I am including what it looks like after the pool guy tried and it ate off the glazing.