Lo Chlor - Pool Algaecide is guaranteed to reduce the need for costly chlorine and shock usage up to 90%. This powerful algaecide kills and prevents all types of algae, including chlorine-resistant species, and lasts up to 90 days with just 4 treatments a year. It has a non-staining formula and is safe for all pool surfaces. Each 16 oz. bottle treats 10,000 gallons, perfect for pools of any size. Lo Chlor - Pool Algaecide is the best value of all algaecide formulations.