Greetings friends. I want to get my asphalt shingle roof cleaned - not pressured washed. I have been doing some on-line research as well have had three roofers out to my house - all are giving me a different (in their opinion the only option for me) treatments. One says they will use a lower pressure water (1200 psi) to clean off the algae, the second has told me they will apply a product that can take up to 6 months after application using nature's elements - wind, rain, and sun to slowly clean the roof, and the third is selling me a product that will clean the algae from the roof and after they will apply Roof-A-Cide that will keep my roof mildew and algae free for two years. What does anyone know about these methods? Thanks much!!!