If you are experiencing an algae bloom, which has turned your pool green, the poolife^® Back to Blue^® shock system can turn your pool sparkling blue again. This two-part system destroys the bacteria and algae that have taken over your pool and then makes it easy to vacuum out. At the start of the season, or if an algae bloom occurs during the season, the pool can be treated and returned to its clear blue appearance within 24 hours by using poolife^® Back to Blue^® I and poolife^® Back to Blue® II as part of the poolife^® Back to Blue^®shock system.