CuZn The Spa Mineral Purifier for Spa, Hot Tub and Jacuzzi New Spa CuZn Cubes System! Replaces Prior 4" Disc Version to Improve Compatibility with Skimmer Baskets of All Sizes (no skimmer basket in your spa? search ASIN# B000NBOPFW) (Have a swimming pool too? Search ASIN#B000HHPQ3C) Balances pH, Controls Bacteria & Algae Growth, Removes Existing & Prevents Future Hard Scale Build Up This Mineral Based Water Treatment System Requires No Plumbing, Installs in a Matter of Seconds. The Following Products are Typically All That is Needed When Using the Spa CuZn System: Scum Bug, Clarifier & Potassium Monopersulfate Based Shock 60 Day Money Back Guarantee! If You aren't Completely Satisfied with The Spa CuZn, We'll Give You a Full Refund Eliminates the Need for Chemistry, Testing & Nearly All Expensive Chemical Additives. Simply Add a Non-chlorine "Mini Shock" on a Weekly Basis (see product description below for details)