This is a highly effective, multi-purpose product that sanitizes,clarifies, helps prevent algae and shock treats your pool. It is convenient, easy to use, and won?t over-stabilize your pool. For crystal clean pool water, follow our 4 step pool care program: Step 1: Test and adjust pool waterbalance, Step 2: Chlorinate and clarify, Step 3: Shock treat your pool at least once a week, and Step 4: Add algaecide regularly.Additional shocking to keep water clean and clear is recommended after: rain and heavy winds; high number of swimmers; increased water temperature; and/or increased frequency of pool usage.