I just used a product I got from Home
Depot called M1 roof and deck cleaner..
Did not think it would do much to the
black spots(from trees) and the moss
on the edge of the shingles...Tried it..
WOW...looks like it is doing nothing
until you start to wash it off..Looked
great, now I have to do the rest of the
roof to match the new look of the clean
spot.