Our Algaecide is an excellent general purpose long life algaecide that kills and protects against all forms of algae for up to 3 months. This product eradicates and prevents algae (blue-green, black and mustard varieties). Three monthly doses is normally sufficient. This is effective over a wide pH range. Users also notice a significant clarifying effect. Lo-Chlor Pool Algaecide is compatible with all pool chemical treatments. Pool Algaecide is also an excellent booster for salt water chlorinators. This is a 1-quart bottle. Each 8 ounces will treat 5000 gallons of pool water.