Remove small topical stains from pool plaster require getting in the pool. Our Pool Plaster Diamond Sanding Block fits your hand perfect allowing you to apply pressure as needed. Unlike all other sanding blocks our diamonds are bonded NON-CORROSIVE material. Can be used above or below the waterline. Every plaster swimming pool should have one. It also helps to have a mask to make it easier to see. Stain removal block works great on topical stain removal on swimming pool plaster. Last 3 times longer than Pool Stone with no residuals remaining in the pool. Pool Plaster Polishing Pads.