One thing that I have learned in my ten years of bein in business is that there’s no such thing as magic.  Other roof cleaners are telling people that a product will kill the moss and wash it away.  Not true!  The moss will turn brown and stay there looking uglier then before.  It will come back to life in 6 months to a year.  Hire a licensed roof cleaner for Portland Oregon roof moss.  You and your roof will appreciate it.