Pool Plaster Hand Disc is the best method for removing stains on pool plaster that requires getting in the pool. Not a bad option when it is hot! You will need our pool plaster hand pad. The Most Common Cause of Pool Staining is metal corrosive materials mixing with the ph levels in swimming pool water. All discs use a corrosive metal for diamond bonding unless specified because of the cost. That causes rust problems from the residuals most of the time after use. Our diamonds are bonded with a NON-CORROSIVE material. Its foam block fits your hand perfectly which allows you to apply pressure as needed. Every plaster swimming pool should have one. It also helps to have an underwater mask to make it easier to see the stain. The pool plaster hand disc stain removal block removes all topical pool plaster stains with just a few passes. The product can be used above or below the waterline. It lasts 3 times longer than Pool Stone with no residuals remaining in the pool. Medium Grit. Pool Plaster Polishing Pads.