We have a trex deck that got mildew stains in just a few months. It is now 15 months old and I am sorry that I ever chose it. First we were told to try Olympic Deck Cleaner--it works, but only for a short while. Next, Trex sent us a "free supply" of a new product that they said would clean the deck. Nope--the stains are as black as ever. Now, I am waiting for a Trex rep to contact me about the problem. I'm not "holding my breath" waiting. I would never recommend this decking product to anyone.