Simply spray it and forget it. The revolutionary no rinse cleaner that removes green and black stains caused by algae, mildew, fungus, and lichen from roofs, siding, decks, brick, stucco, and other exterior surfaces. It is biodegradable, noncorrosive, and does not require damaging power washing and/or brush techniques. In fact, no rinsing is required and your landscaping will not be compromised. Does not contain any caustic chemicals such as bleach, lye, heavy metals, or acids. 1 gallon makes up to 10 gallon of cleaner/preventive. Covers approximately 1000 sq. ft. per gallon.