mold?

[cclllc]

I have a customer who has a rock porch and walls on the front of her home.I seems to have a mold on it.it is black.She thinks it is leaf mold where the gutters may be runninig over.Is she correct and what will clean it.Thanks,john

 

[cclllc]

How would bleach do on the stone?

 

[klean_freak]

No one responded to you yet??

well in my exp. bleach on stone is fine but watch plants and vegetation.
water them down before you bleach or other chems??

Just my 2 cents