Dry Cleaning Fiberglass Roof

I think it's probably fine for light soil levels, but for what I just cleaned off the roof of mine this past weekend, it would never have even touched it. I spent about 2 hours on my hands and knees with a rag scrubbing every inch of the roof to get the tree mildew off of it. I didn't realize how bad it had become until I got up there to clean out the ceiling vents of leaf debris that had sucked into them. And honestly, I could spend ANOTHER 2 hours up there doing the same thing before it's ready to wax.....but I simply gave out and made a promise to get up there another day. I might invest in a lightweight young person that wants to make $50....... :-)