Non-foaming algaecide kills and prevents all types of algae and slime growth. Spa Algaecide is compatible with chlorine, bromine, ozone and biguanide sanitizers. Initial Treatment: For visible algae growth or slimy interior surface, add 6-8-ounce per 500 gallons. For heavy algae growth, drain spa and clean prior to treatment. Maintenance Treatment: Add 1-2-ounce per 500 gallons every 5-7 days.