I have a 2,500 square foot TimberTech composite deck in Toronto Canada. I installed it in 2015 or 2016? No one told me it got moldy when I bought it, especially on the north side of the boat house! I tried the sodium hypochlorite chlorine bleach based products. Don't waste your time! After doing a lot of research on the internet, I finally found Corte Clean. It was the only website that explained the problem as it relates to the wood fiber tannin's and molds. This was the deciding factor in going with Corte Clean. Unfortunately, there wasn't a retailer near me, so I drove approximately 2 hours, each way, to the 84 Lumber in Buffalo, NY. They only had 2 bags of Corte Clean or I would have bought more!!! I took them home & used them. The label directions are crystal clear. This is the only product that works. I know a lot of people with composite decks and will be recommending this product. I just ordered 8 more to complete the job this spring. Thanks Corte Clean!