I just posted this over on our Google+ that Chris Tucker made for us. Learn what the black discolorations actually are, how to remove them and how to pronounce "Gloeocapsa_magma"
http://roofcleaninginstitute.org/index.php?/blog/33/entry-411-shingle-tile-roof-cleaning-black-discoloration-explained/
Here is how most of us at RCIA remove it - https://www.youtube.com/watch?v=AVakZwBLwUc
-- Edited by Bergman Roof Cleaning Port Charlotte FL 941-698-1959 on Saturday 17th of January 2015 01:07:58 PM
Serving Englewood Rotonda North Port Cape Haze Venice Port Charlotte Punta Gorda Boca Grande Charlotte and Southern Sarasota Counties in Florida.
941-698-1959www.bergmanroofcleaning.com
http://www.youtube.com/watch?v=4RNlN3R7CqI