The answer to 'why is my ridge vent algae growth' is that algae growth on ridge vents is a common problem caused by moisture, shade, and organic debris buildup. Algae thrive in the damp, dark conditions often found on ridge vents, and can lead to unsightly staining and potential issues with airflow and ventilation.
To address algae growth, you'll first want to inspect the ridge vent and surrounding roof area. Look for any debris, leaves, or other organic matter that may be collecting and holding moisture. Trim back any overhanging trees or vegetation that could be contributing to shade and dampness. You can also try using a soft-bristle brush or pressure washer to gently clean the vent, being careful not to damage the vent itself. In some cases, applying a roof cleaning solution designed to kill and prevent algae growth may be necessary. However, if the algae problem persists or you're uncomfortable working on your roof, it's best to call in a professional roofing contractor to properly assess and address the issue.