Everything You Need to Know About Blue-Green Algae

By Stacy Mellete

Blue-green algae (Gloeocapsa magma) is a common type of algae that grows on asphalt shingle roofs, leaving unsightly dark stains as they spread. In this blog, local roofing company in Tampa,  Affordable Roofing Systems shares an overview of what blue-green algae is, how to get rid of it, and what you can do to prevent it.


Blue-Green Algae

Algae is a species of bacteria that has plant-like qualities, such as photosynthesis and subsistence on moisture. Blue-green algae is an airborne species that thrives on open-air surfaces, including rooftops. A dark outer layer protects them from UV rays and heat from the sun. This is the same black substance that causes the black streaks that you see on the roof. Blue-green algae subsists on moisture and limestone filler found on asphalt shingles. It may not have severe effects on the roof, but blue-green algae does make any asphalt shingle roof look ugly.

How to Get Rid of Blue-Green Algae

If your roof already has those unsightly black streaks, don’t worry. There are several ways to remove them:

  1. Hire a roofing contractor that offers a roof cleaning service for your residential roof. This is probably the safest route, as a roofing contractor will know how to properly clean your roof and avoid doing anything that might damage your roof.

  2. Spray the roof with diluted bleach or a commercially-available roof cleaning solution.

  1. Use a pressure washer at low settings. Caution must be exercised when using a pressure washer, as granules can get dislodged even when you’re using medium-to-low settings.

  2. Install zinc strips. Roofing manufacturers offer zinc strips that can be installed at the roof ridge. Zinc particles get dispersed onto the roofing surface when it rains, which kills blue-green algae.

GAF StainGuard Plus Shingles

Roofing manufacturer GAF offers an alternative for homeowners who are planning on buying a new roof, and would be happy not to have to deal with blue-green algae at any time in the future. GAF StainGuard Plus™ Shingles contain algae-fighting copper capsules blended with the roofing granules. While there are similar roofing products, StainGuard Plus Shingles feature a proprietary Time-Release technology, which releases copper particles slowly and consistently over its service life.

Affordable Roofing Systems is your leading provider of roof repairs and installation services. Give us a call at (813) 542-8462 or fill out our contact form. We serve customers in Clearwater and Tampa, FL.

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