Applied Biochemists Swimtrine Plus is a powerful, high concentrated algaecide that uses natural copper to kill off mustard and green algae growth. When used regularly, it also prevents the regrowth of all types of algae. Its liquid formula is super concentrated to stretch one bottle for each season in most pools, and needs no special balancing to remain effective. Best of all, Swimtrine Plus is made by Applied Biochemists, a leader in bio-based pool chemicals, allowing you to buy with confidence.