Get rid of stubborn green and black stains with Wet and Forget bleach-free, non-acidic outdoor cleaner. Just dilute with water, spray it on and forget it. The concentrate is ideal for precise applications on surfaces like sidewalks, retaining walls & fencing. It works with the rain and wind to gently clean up moss, mould, and mildew on any outdoor surface - no scrubbing or rinsing required. In most cases, surfaces stay clean for 1+ years after treatment. Makes 24 liters total.