Blue-green algae, also known as gloeocapsa magma, affects more than 80% of roofing systems in the country. It leaves dark black stains wherever it grows and makes millions of perfectly good roofs look old way before their time. 

As a GAF Master Elite® roofing contractor, Thompson Roofing and Construction is no stranger to this unsightly growth. Gloeocapsa magma may be blue-green in color, but it is surrounded by a dark brownish-black shell that protects it against the sun’s rays. Over time, these dark shells cause the telltale streaking on the roof.