Wet & Forget Outdoor Cleaner eliminates tough mold, mildew, and algae stains. Mix 5:1 with water in a tank sprayer and apply to sealed outdoor surfaces. Wet and Forget's bleach-free formula goes to work with the wind and rain to gently clean over time with no rinsing or scrubbing. Delivers an extended clean - up to 1 year or longer. 1-Gallon concentrate makes 6-gallons and treats 750 to 2,250 sq. ft. Ideal for cleaning roofs, siding, decks, walkways, patios, outdoor furniture, painted surfaces, vinyl, aluminum and more.