Aqua Chem 22816AQU Shock Plus Water Clarifier for Swimming Pools, 1-Pound Creates sparkling water, For all pool surfaces, Reduces chlorine odor and eye irritation, Does not increase pH All-in-one shock that produces clear, sparkling water in your pool when added on a weekly basis There's no need to pre-dissolve Shock Plus and you can resume swimming in as soon as 15 minutes after adding