The answer to 'roof vent algae growth' is that algae growth on roof vents is a common problem caused by moisture, shade, and poor airflow. Symptoms include green, black, or reddish slime or discoloration on the vent. This can lead to reduced ventilation and potential damage to the vent and surrounding roofing materials.
The best solution is to clean the vent regularly and improve airflow and drainage around the vent. This may involve trimming nearby trees or shrubs, clearing debris, and ensuring proper ventilation. In some cases, replacing the vent may be necessary if it is severely damaged or cannot be adequately cleaned. For extensive algae growth or difficult-to-access vents, it's best to call a professional roofing contractor to assess and resolve the issue.