What kills algae on shingle roofs?

What kills algae on shingle roofs most effectively are oxygen bleach based cleaners and copper or zinc based algaecides that are shingle-safe and do not strip granules. For black algae streaks caused by Gloeocapsa magma, the industry standard recommended by manufacturers like GAF and Owens Corning is oxygen bleach, sodium percarbonate, mixed with water and mild dish soap, applied with a garden sprayer, allowed to dwell, and rinsed gently with low-pressure water. This kills algae through oxidation without harsh chlorine. Commercial products specifically formulated for asphalt shingles are highly effective, including Spray and Forget, Wet and Forget Outdoor, and Roof Shampoo, which use surfactants and slow-acting agents that kill algae over weeks with rain and require no rinsing or pressure washing. Products containing zinc or copper, such as zinc sulfate or copper sulfate, are also effective as they create a toxic environment for algae. Shingles with built-in algae resistance like Atlas Pinnacle Pristine with Scotchgard Protector use copper-containing granules that continuously release algae-inhibiting ions. For prevention after cleaning, installing zinc or copper strips near the ridge provides long-term control as rain washes metal ions down the roof. Avoid chlorine bleach in concentrated form, as it can damage shingles and corrode flashing, and never pressure wash algae, which removes protective granules and voids warranties.