Betty wants to sell her home. I'll never know why poeple wait so long. We cleaned the roof, washed the mold from the vinyl siding, cleand and whitened the cement in the front porch area and in the back, pressure cleaned the Trex surface of the deck, prepped the wood railings and spindles and applied 2 coats of Cabot wood stain/waterproofing sealer. Black algae on the roof will remove instantly. This roof is also covered with moss. Treated moss and lichen will turn white and dry out. It will remove naturally. This roof will get cleaner with each rain. The whole process can take up to 6 weeks. This roof was cleaned without the use of a pressure washer. All detergents are manufacturer approved. Total cost of job was $1114.00. Good luck on your sale Betty!