Regal Chemicals 47247000 50 lb 3" Xtreme Tabs - Premium pool care programs offer improved water quality, fewer issues and easier pool ownership. Regal Xtreme Tabs are slow-dissolving blended chlorine tablets that kill bacteria and control algae, but also act as a clarifier and prevent unsightly staining and damaging scale from forming. It also acts as a clarifier and prevent unsightly staining and damaging scale from forming.