Tips for Dealing with Black Algae Stains on Your Shingle Roof

If you notice dark stains forming on your roof that seem to streak down the shingles from the top ridge all the way down to the roof base, then you may think that the stains are produced by dirt that has washed down the top surfaces of the shingles. However, dirt is rarely the cause of the problem. The issue usually develops due to the formation of a blue-green algae that typically appears dark green to black in color.