The answer to 'downspouts algae growth' is that algae buildup in downspouts is a common problem for many homeowners. This can be caused by a combination of moisture, dirt, and lack of proper cleaning and maintenance. Symptoms include green or black slimy growth on the inside of the downspout, which can restrict water flow and lead to water damage or basement flooding.
In most cases, homeowners can address this issue themselves with some basic cleaning and maintenance. This typically involves removing debris, scrubbing the downspout with a stiff brush and mild detergent, and flushing the system with a garden hose. However, if the problem persists or the downspout is difficult to access, it's best to call in a professional roofing or gutter cleaning service to ensure the issue is properly resolved.