How many ozs of algaecide per 18000 gallons of water?

The amount of algaecide needed per 18,000 gallons of water can vary based on the specific product and its concentration. Typically, manufacturers provide guidelines on their labels. Generally, it's common to use between 1 to 2 ounces of algaecide per 1,000 gallons, which would equate to about 18 to 36 ounces for 18,000 gallons. Always refer to the product’s instructions for the most accurate dosage.