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You may read stories about using "THE NEW SALE PRODUCT OF THE MONTH" Here today and gone tomorrow, so called "Geen, Eco-Friendly, BioDegradable, Bla Bla Bla.

Most will tell you that your roof will magically look clean, not when they take your money and leave, but in 3 months to a year! Plus, most will start up their pressure washer in the end and tell you stories about why it's OK.

These salesmen will say ANYTHING to sell you their untested products.

They even say that the manufacturers of roofing only recommend Chlorine and TSP because they want your roof to fail early, so you have to replace it. 

That's just plain dumb!

Roofs come with warranties, so if the manufacturer suggests you use chlorine and TSP to clean it and it fails prematurly, the manufacturer has to honor the warranty-THAT IS NOT WHAT THE MANUFACTURER WANTS OF COURSE!

These "Go Green" salesmen just make up anything that comes to mind to make easy money.

THIS IS WHAT THE MANUFACTURERS OF YOUR ROOFING SAY TO DO TO CLEAN YOUR ROOF.

YOU WILL FIND PROOF HERE, NOT A SALES PITCH. WE ARE NOT SELLING ANY CHEMICALS HERE!

From GAF Roofing Manufacturers about black algae removal:

http://www.gaf.com/Documents/Algae_Staining_on_Shingled_Roof_Surfaces_-_Steep_Slope_Techn-43-808-v3.pdf

Below is a partial "cut and paste" excerpt from GAF on how to clean a roof:


"If a new roof is not an option, GAF recommends cleaning the roof with a special mixture. That mixture is:
4 gallons of water, 1 gallon of bleach and 1 cup of TSP"


"What NOT To Do! Do not power wash the shingles to clean the shingles. Some roof cleaning companies offer this service.
However, it is not recommended."


From ARMA roofing manufacturers Association-how to clean roofing.

http://www.asphaltroofing.org/pdf/tb_217.pdf

Below is a partial excerpt cut and pasted below from ARMA:

Algae discolorations to remove from roofing surfaces, applying a solution of
chlorine bleach, trisodium phosphate, and water. Solutions for these ingredients depend on the amount of discoloration. Solutions range to one cup TSP and 2.5 gallons each of bleach and water.

{Note that they are suggesting up to 50% chlorine! 2 1/2 water & 2 1/2 Chlorine}
First, gently disperse this solution on the roofing surface. Avoid scrubbing the surface, as this friction may loosen and remove granules.
Caution!
High pressure washing systems for algae removal should not be used.

Owens Corning Roofing manufacturers says the same thing:

"USE CHLORINE and TSP" "DO NOT USE A PRESSURE WASHER"

Corning info in link below.
Click Link, Go to "Do I need a New Roof" Then to "Algae growth" and read what the manufacturer says on the right side of the page.

http://webapps.easy2.com/cm2/flash/generic_index.asp?page_id=36077811