What could be done to clean black staining from red brickwork?
Bleach works well . I dilute it 50 to 65 % and spray on red brick and concrete drive way. In my warm humid climate ,the brick gets green algae and some dark mold every year ( I usually need to spray only about 5% of the brick). The driveway gets dark ,apparent mold , and needs 100 % coverage. I use a 3 gallon hand pump garden sprayer. It will reach up about 20 ft.