This is an effective, 4-in-1 shock product that kills bacteria & algae & restores crystal clear pool water within 24 hours, reduces chlorine odor & eye irritation caused by swimming pool water & won't fade liners. It is 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. Note: use entire contents of bag when opened. Do not use in floater or feeder.