Well, here's my story: Called UltraGuard today, lady took my number and said the guy would call me back, which he did within an hour. I explained about my inground 17' x 34' x 8'deep (at one end) pool, concrete bottom with 3' sides that were supposedly laminated porcelain on steel. Explained pool was built in 1962 and that I had maintained pool completely by myself since 1975 (when we bought the house). Explained that concrete was solid with no cracks, and that the sides had developed 2-3 dime-quarter sized holes that I had successfully patched with PC-7. Had ground paint off pool bottom 4-5 times over the last 32 years, painting with Poxolon, then switching to Ramuc acrylic water-based in 1992. Had lightly sanded bad spots on sides in 1992 and painted completely with Poxolon, switching to Zeron in 2003. Had nice intelligent conversation, no screaming or yelling, etc. End result--Guy flat out refused to sell me the product---said what I'd been doing was fairly successful and to stick with it. Got to admit, I was dumbfounded. Over the years of grinding down, I figure I've lost 1/8 to 1/4 inch of concrete, which has exposed pieces of what I would call sandstone--these small areas seem to hold moisture (from both sides), which is where the paint tends to bubble and flake after a few years, and that's why I wanted to try the UltraGuard. Wow--almost seems like there are laws about not selling your product to certain people. Upside--wife will be happy I'm not blowing $1500+ on UltraGuard.