I am writing to let you know how pleased I am with Corte Cleaner. I have a composite deck made with grey colored Weyerhauser ChoiceDek. At the end of last summer, it started to get black spots on it. I didnt think it was mold because it gets so much sun light. But I used some bleach on it and that seemed to help, but it did not remove it completely. Then this Spring, the black spots really began to spread. So once again I tried the bleach method, and although it remove the mold, within weeks it was back. Discouraged, I tried some Olympic deck cleaner, which again, removed the mold some, but not completely. And, because it is such a strong chemical, I began looking for something else. Thats when I came across Corte Cleaner on the web and decided to try it particularly since is specifically for composite decks. I must admit, after what I had been through, I was skeptical that anything would work. Well, my skepticism is gone. Not only was Corte Clean easier to use than anything else I had tried, but it was also not a harsh chemical you needed to wear haz-mat gear with. When I applied it, I could begin to see it work because it turns the black into like a brown foam, so you can see it doing its thing. I did use a brush and scrubbed the areas sprayed and it worked great. I was VERY PLEASED and will not use anything else on my deck. One last thing. There was an area of my deck I had cleaned with the Olympic deck cleaner and not Corte Cleaner. Now, about a month after using both, the area cleaned with Olympic is beginning to show a return of the mold, but not the area cleaned with Corte Cleaner. Last time the mold returned, I was very discouraged that I would have to live with a moldly deck. Well, now that I have Corte Cleaner, I am clear I can keep my deck looking good. Thanks for a great product.