Although these dark spots and ugly black streaks on your roof may look like dirt mildew soot or mold what they really are is algae.
Remove green and black patches from gutters.
It attacks the oxidation and not the paint or material.
Scrub the gutters with the soap mixture to clean them.
The most common type is known as gloeocapsa magma also known as blue green algae.
Simple green makes a concentrated environmentally safe cleaner with good stain removing properties.
Rust residue dirt buildup and corrosion can all be removed by scrubbing the gutters clean.
It can present as green dark brown or black patches and streaks or fuzzy looking stains.
This algae growth usually begins as small spots and then eventually becomes visible streaks.
F 13 gutter grenade is a multipurpose gutter cleaner that s safe for all types of gutters.
The black streaks are a result of electrostatic bonding of tar asphalt from roofing material and other debris to aluminum metal material.
These may require you to vigorously scrub or make take several attempts but it can all be removed.
For aluminum try gutter zap which removes electrostatic bonded streaks with little scrubbing.
Check around your gutters around windows and doors and along the base of your walls.
Streak getter will break down this bond which will allow you to remove the unwanted streaks off your aluminum gutter with little effort no scrubbing.
They prevent water from getting into your basements or crawlspace and protect windows and siding especially wood from extreme water penetration.