Clorox 33012CLX Pool&Spa Shock, 12-Pack Easy open, easy pour bottles Contains blue algae killing crystals Kills and prevents green, black and mustard algae Kills &amp; controls green, black &amp; mustard algae Kills bacteria Clears cloudy water and removes swimmer contaminants Reduces chlorine odor and eye irritation Improves filter performance Won&#039;t impact pH 1-pound bottle treats 12,000 gallons of water Recyclable, resealable, easy-open, easy-pour bottles