I have tried everything I knew of to clean my parents deck. They had Timberteck decking installed. The deck is mostly in shade and surrounded by trees. I would have to pressure wash it every year due to the sap, leaves, and debris from the trees. After a few years, I found a few areas where it just would not come clean like it used to. Found out that these area retained water for longer periods of time and became moldy. I tried soap, lemon juice, baking soda, and mild detergents. Nothing seemed to help. I searched online for other possible solutions and found Corte Clean Composite Deck Cleaner. I decided to order and give it a shot. All I can say is - WOW!! The areas are clear and the deck looks like its new again. I filled the sprayer with the solution and sprayed the deck. Following the instructions of keeping the area wet and giving it time. I did use a medium/soft bristle brush to lightly scrub the bad areas. The results are amazing. Thank you Corte Clean. I have already recommended the Composite Deck Cleaner to friends and family that have composite decking and they have had similar results.