Get rid of stubborn green and black stains with Wet and Forget Outdoor. Just dilute with water, spray it on, and forget it. The Wet and Forget Outdoor Concentrate is ideal for precise applications on surfaces such as sidewalks, retaining walls and fencing. Wet and Forget works with the rain and wind to gently clean up moss, mold, mildew and algae on virtually any outdoor surface. No scrubbing or rinsing required. In most cases, surfaces stay clean for 1+ years after treatment with Wet and Forget. The Wet and Forget Concentrate makes 6 gallons total. Wet and Forget is bleach-free and non-acidic. Wet and Forget 1-Gallon Multi-surface Concentrated Outdoor Cleaner | 800006