Need roof cleaning help

[IwannaRV]

Hi all,
I haven't been here in a while. Hope you are all well.
I went up on the roof to have a look and found lots of green and black stuff. I think the roof should be white but it is mostly black now. I mixed 50/50 Simple Green and started to scrub it down. It works on the green stuff but not so well on the black stuff which is on the flat part of the rubber roof. It is thin and smooth and hiding the white roof underneath. Simple Green works ok on the green stuff which I think is algae but what is this black stuff? Is it mold? Is there a better product to use? I was in Home Depot and saw a product by Zep called Mold and Mildew remover. Will that work better? I can scrub and scrub with the Simple Green but this black stuff is really tough and I am not making much of a dent. Do I have to remove all the black stuff before applying the Dicor? Thanks!

[RV Roamer]

The black stuff is another type of algae, or perhaps accumulated crumbs of leaves and dirt, or a combination of all of those. Add some bleach to your Simple Green solution and make it fairly strong, at least a cup per two gallons. And use a scrub brush with a medium bristle ( along handle one is easier, but any kind will do).

[Fred G.]

I don't know how would it affect your rubber roof, but on my fiberglass roof, I spray undiluted bleach and let it sit for about 15min. The bleach kills the mold and bleaches it. After that, I rinse with a soft brush to remove all traces of bleach.