Use bleach or liquid pool shock(sodium hypochlorite) and T.S.P. or Jomax in a pump up sprayer.
Wet roof FIRST and all surrounding plants, bushes, grass etc. with plain water...then apply mix to roof. Let the chemical do the work. Sometimes a second application is needed.
Don't be afraid of the bleach....it will NOT hurt asphalt shingles and is the ONLY thing that will work.
bleach is 6% sodium hypoclorite
liquid pool shock is about 12% sodium hypoclorite
I buy pool shock at Ocean State Job Lot to do all my exterior cleaning.
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