Trex is just terrible stuff. I spent a fortune for this deck and it looks terrible all the time. The mildew is pervasive. I followed the Trex Co.'s instructions to the letter and the cleaning lasted lest than two weeks. The mold came right back after cleaning. AND, it is impossible to clean just a small portion of this deck. Once cleaning begins, the entire deck must be cleaned or the difference in the bleached portion and the non-bleached is glaring. AND, pressure washing won't work because the pressure from the washer makes marks on the deck. The worst.