I purchased Clorox Composite Deck Cleaner from the Home Depot to clean my Trex deck of black mold, flower pot and other stains. It had little if any effect. I then found Corte Clean in the TREX literature. I ordered it from this web site to give it a try. I was amazed at how well it worked although it did take several applications to clean the tougher stains. I just ordered another 12lbs. Great product!