How to Clean Algae From the Roof

• 1). Mix 1 qt. oxygen bleach and 1 gallon of water in a bucket, and pour it into the pump-type garden sprayer. Mix the solution well. It's important to use oxygen bleach because it will not discolor your shingles and is not toxic.
  
  
• 2). Begin spraying the solution until the roof is saturated. Allow the bleach mixture to set for at least 15 minutes.
  
  
• 3). Use a hard-bristled push broom to scrub the shingles clean. You may have to re-wet areas of the roof with the solution.
  
  
• 4). Rinse the roof using a garden hose with spray nozzle. If the algae is still visible on the roof, you may need to treat it several times.