The answer to 'architectural shingles algae growth' is that algae growth on architectural shingles is a common problem caused by moisture, shade, and organic debris. Symptoms include dark green, black, or reddish-brown streaks or stains on the shingles. While this is primarily an aesthetic issue and does not typically affect the roof's performance, it can detract from the appearance of the home.
The best solution is to regularly clean the roof using a soft-bristle brush, diluted bleach solution, or professional roof cleaning products. This should be done every 1-2 years to prevent buildup. In some cases, moss or lichen may also need to be removed. If the algae growth is severe or recurring, it's best to consult a professional roofer to determine the underlying cause and proper treatment.