Hi Scott, Well, we used the Corte Clean following the directions on the can. The stuff is amazing! As you can see from the pictures, we had really bad black mold spots all over our Smart Deck composite decking. It is true — the stuff works the best in sunlight. I mixed 2 cupfuls of Corte Clean in a gallon of hot water, sprayed it on and let it sit 25 minutes, brooming it once after about 15 minutes, and sprayed on more mixture after brooming. You can see the color difference and how clean the deck became. I used all of the Corte Clean on a very dirty 14 ft x 16 ft deck, and ran out before I could finish the other 16 ft x 16 ft portion of my deck. So I am ready to buy more. Please stock this product! Once the word gets out, look out! It’s the ONLY PRODUCT I’VE FOUND THAT WORKS without bleaching the composite material. Thanks for the opportunity to provide this testimonial and I look forward to a bright-shiny deck from now on! Let me know when you get more product — I’d like to keep at least a 10 pound supply on hand. Thanks Corte-Clean, and thanks to The Deck Superstore for offering this product. Sincerely, P. Thompson, Centennial, CO 8/17/2008 SmartDeck Composite deck owner — deck installed in 2003 and this was the 1st time it actually came clean!