I have had a Trex deck for 17 years. It was installed in 2000. It didn't get dirty for the first few years here in ON, Canada. Then it got mold and other stains. I tried many products, at the recommendation of the Trex Company. They contained sodium hypochlorite and oxalic acid. They temporarily only bleached out the mold. When the deck received moisture it came right back, costing me more time and money to again clean. Season after season it got worse, until it took over the deck. I then discovered Corte Clean at a retailer. I haven’t found anything that works as well, for as long, and proactively using it is the key. I just phone ordered 3 more bags. Proactively applying Corte Clean costs less money and time to keep my Trex deck clean.