I have a lot of houses that i turn down because of lichen stains in my area (NJ) How do you guys remove this without removing the granuals from the roof? I have tried heavy batches of SH but doesnt seem to work. What am I doing wrong? Black streaks are not a problem. we have a big problem in my area with this. Is there any othr chemical out there that will kill this mold without disturbing the roof granuals?