"Gloeocapsa Magma is the true culprit that causes black streaks on roofs and surfaces. Other forms of microorganisms can be found in union with the bacteria, including mold, fungi, algae, mildew, lichen, and moss. The main culprit of most roof staining that causes prevalent black streaks is a bacteria called Gloeocapsa Magma. Many of the organisms that grow on a roof, including mildew, algae, bacteria, moss, lichen, and fungi, copulate in the warm, moist environment created by a roof.
Plus, many roofing surfaces are made with materials that can be metabolized by these microorganisms, such as shingles that now contain limestone that algae, mildew, and bacteria will absorb their nutrients and feed off the shingles.
That same Cyanobacteria Gloeocapsa Magma found on roofs will grow on wood, concrete, siding, aluminum, and other surfaces as well. The good news is that through soft washing, these stains/microorganisms can be safely removed! In regards to other possible culprits inhabiting a roof, many nitrogen fixing blue-green algae will grow in areas with little to no nutrients. They are able to sustain themselves because nitrogen fixing organisms have the ability to create nutrients solely through the nodules on their filament root systems. That is why here at SoftWash Systems, we believe that treatment of a roof or surface is more beneficial to rid the source of the staining rather than just blasting away at the surface!"
Found this at www.Softwashsystems.com
The problem as I discovered is getting a strong enough solution on the chimney, and then getting it to stick to the verticle surface long enough to kill the organisms. That chimney’s short enough that you could always use a pump up sprayer to apply a strong solution if you don’t have DSI or XJet. You will need something to make it stick. If you have nothing professional, try Dawn.