1 lb. Box TSP Heavy Duty Cleaner - The Home Depot
Rated 5 out of 5 by LisaG from TSP---- Total Super Product By far the best cleaner for outdoor items like siding, vinyl patio furniture, grimy sidewalks and most of all, gross filthy decks! I even cleaned a teak bench that was black with grime. I have used nearly every deck/siding cleaner on the market, but nothing beats TSP ability to eat through dirt and grime that cannot even be scrubbed away.