Hth, 6 pack, 13.3 oz, shock treatment bag, effective, multi-purpose product that sanitizes, clarifies, helps prevent algae in your pool, convenient, easy to use, won’t over stabilize your pool, for crystal clear pool water, follow our hth 4 step pool care program: step 1: test & adjust pool water balance, step 2: sanitize, step 3: shock treat your pool at least once a week, step 4: add algaecide regularly.