The reason is this particular type of blue-green algae is responsible for creating the unattractive black roof stains and/or streaks commonly noticed by many. The blue-green algae, unicellular, 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 primary reasoning behind the rapid spread and noticeability of this algae in the Tampa Florida area are:
1. Rising humidity and temperatures in Tampa combined with more and more bacteria spores promotes 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 blue-green algae have become noticeable, the stains will continue to worsen year to year. There is debate over the actual harmfulness of this particular blue-green algae to roofs, as there is little supportive scientific research. However, most "experts" within the subject area conclude the blue-green algae to be harmful, if left untreated, as the growth holds moisture within shingles causing premature aging, rotting, and/or granule loss.
APPLE ROOF CLEANING TAMPA
7401 Patrician Place
Tampa FL 33619