The answer to 'ridge vent algae growth' is that algae growth on ridge vents is a common problem, often caused by moisture, shade, and lack of airflow. Symptoms include black, green, or reddish-brown discoloration on the ridge vent. While this is primarily an aesthetic issue, it can eventually lead to premature wear and tear on the vent components.
The best solution is to clean the ridge vent regularly using a soft-bristle brush, mild detergent, and water. This can often be done as a DIY project. However, if the algae growth is extensive or the ridge vent is in poor condition, it's best to call a professional roofing contractor to inspect and potentially replace the vent.