Handsomedan:

 

Wet and Forget. 

 

It's easy to apply and seems to smell like it would work...but there's no immediate effect. I want instant gratification! 

 

I don't like having to wait for progress. 

 

Just use diluted Clorogene. We had a quote from a well known roof cleaning company of circa $900 to remove lichen and other stuff off our roof. My ever resourceful wife diluted clorogene with water in a spray bottle thing, climbed on the roof, sprayed, came down had lunch and a few weeks or so later it was all gone. All up it cost a lot less than $100.

We use this to clean our driveway, lichen off the Glass House and other so called wet and forget tasks.