D. Schone 

My trex deck had the black spots, was vert dirty, had what I believe is lichen and a green coloration in places which I took for algae. I have used your product and all of this has been lifted off. Conditions were not ideal given the September sunshine, and only a half day at that due to the deck’s location and given the shade from the trees, and I did scrub on the hardest spots since I knew that the optimal conditions were beyond my reach. I am really satisfied with the results.