Unlike roof moss which is easily identified, a hardy species of algae called Gloeocapsa Magma causes black streaks and stains to form on your shingles as it spreads. The algae feed on the limestone filler that roofing manufacturers use in the asphalt shingle production process. Rain spreads the algae down the roof causing unsightly black streaks. Left untreated, the algae will continue to spread and shorten roof life, increase your energy costs and reduce your property value. As algae grows on your asphalt shingles, it eats away the base of the shingle and begins to expand and contract with outdoor temperature. The growth and movement loosens the shingle granules, causing premature granule loss – which dramatically shortens the life of your roof. Roof stains are an indication that your shingles are being damaged, significantly reducing the lifespan of your roof. Left unchecked, the algae build-up can significantly diminish your roof’s reflective properties. The resulting heat build-up damages the roof and increases summer time energy costs as your air conditioner strains to cool.