Strong detergent for cleaning Composite Decks of dirt, mold, "Slippery Slime" Algae & some grease and BBQ stains.  Label provides instructions for adding limited chorline bleach if Mold and "Slippery Slime" Algae effects your material in your climate.  Put product in a bucket, add warm water, apply to wet deck , brush, then rinse.  Clean and likely much better!!!