Gloeocapsa Magma: The Silent Roof Killer

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Gloeocapsa magma is a species of cyanobacteria. Cyanobacteria are an ancient line of photosynthesizing bacteria, which photolyze water generating oxygen gas. Ancient cyanobacteria were ancestral to the chloroplasts of all plants on earth. Gloeocapsa magma has gained notoriety in the Southeastern U.S. which is quickly spreading throughout the Midwest. This particular type of cyanobacteria is responsible for creating the unattractive black roof stains and/or streaks commonly noticed by many. The bacteria accumulate over time; this accumulation begins to show the problematic black stains as the cyanobacteria develop their dark and hard UV-protective outer coating.

The main reasons for the rapid spread and noticeability of these cyanobacteria are thought to be:

1. Rising humidity and temperatures combined with more and more bacteria spores promote their spread with these favorable conditions.

2. Fiberglass shingles (the most commonly seen amongst today's residential homes) have been being made with limestone as a filler (in the asphalt). These shingles hold moisture and organic "bacteria food" material longer (especially on the North-side in the Midwest) than the paper/asphalt/ceramic shingles of 20+ years ago. Additionally, these particular algae enjoy the limestone as a food source.

Once the bacteria have become noticeable, the stains will continue to worsen year to year. There is debate over the actual harmfulness of these particular bacteria to roofs, as there is little supportive scientific research. However, most "experts" within the subject area conclude the bacteria to be harmful if left untreated, as the growth holds moisture within shingles causing premature aging, rotting, and/or granule loss

Gloeocapsa Magma is an airborne alga so it can land on any area roof with no rhyme or reason, though it does seem to be more prominent in areas holding a lot of trees. Once the roof algae Gloeocapsa Magma lands on the roof, it will have to be killed and removed or it will continue to spread.

The Gloeocapsa Magma will never get better or just go away on its own. The Gloeocapsa Magma algae begin feeding on the nutrients in the shingles.

As it rains the Gloeocapsa Magma spreads down the roof causing black streaks. If not taken care of Gloeocapsa Magma will take over the entire roof in a few short years turning the whole roof black. Besides looking very unsightly and diminishing any home’s curb appeal and value, what other damage can Gloeocapsa Magma roof algae do?  When roof algae are not taken care of they stop the shingles from reflecting heat from the sun’s UV rays. When this happens it can affect your home’s heating and cooling costs without you even realizing it. Also because the shingles cannot reflect heat they start to diminish prematurely. Signs of wear are curled corners, wavy or humped shingles, broke or loose shingles, and an excess of shingle granules appearing in your gutters just to name a few.”

The aforementioned text was taken from a well-known central FLA company’s website.  It is pretty much accurate in what we know both scientifically and practically regarding rooftop algae.  The condensed version of our explanation is as follows:

Gloeocapsa Magma is an airborne alga that originated from Florida.  40 years ago the shingle manufacturer’s used cotton rags and wood chips as the main ingredient for production, however, 30-40 years ago they switched; using limestone instead.  The result was a better product; however, they inadvertently created a feeding source for these algae.  By the time the spores started making their “streaks” and proliferating; it was too late.  The manufacturers completely switched over to limestone and so did their suppliers, eliminating the cotton rag and wood chip industry forever.  Now, the manufacturers have designed their shingles with additives to poison the algae, but those particles wash away between 7 and 10 years from installation, leaving the roof susceptible again.