Dawn dish detergent and soft window washing brush on a pole. If birds attack the deck, I add some Oxiclean powder, use a stiffer brush head, and if mildew shows up, a splash of Clorox to a fresh 5 gallon bucket of second wash water. So far the only thing that doesn’t depart the deck and cockpit after cleaning are the damn spiders. Cindy bought me an electric fly swatter we’re gonna try out this year on the arachnids. Oxi also works on those troublesome red wine spills. Oh yeah... lots of rinse water too!
If you place the Dawn dish soap bottle on deck in an obvious spot while cleaning, the tree huggers leave you alone.