Strong detergent for cleaning Composite Decks of dirt, mold, "Slippery Slime" Algae & some grease and BBQ stains.  Label provides instructions for adding chorline bleach if Mold and "Slippery Slime" Algae is a problem for you.  Put product in a bucket, fill with warm water, apply to deck & brush, then rinse.  Clean!!! Enjoy your Deck!