Nu-Clo Copper 7% - 1 qt. - is a non-foaming pool algaecide. It is designed to kill black, green, mustard, and red algae. Not to be used in pools where mineral issues are present. Used to prevent and kill unwanted infestations. Maintenance is 1 ounce per 5,000 gallons bi-monthly. Use at initial opening of pool or to kill algae/infested water, it is 2 ounces per 5,000 gallons ratio use recommended.