Black algae is perhaps the hardest algae to get rid of. It has very deep roots that can grow into the side of plaster or concrete pools. It also has many layers that . Black algae is a form of algae which is black in color and usually forms in cracks . in plaster surface pools, the surface portion of the algae extending into the . Black algae generally penetrate porous pool surfaces like concrete and gunite. . RUN PUMP - If you have a pool with a light finish, leave the pump off for 24 . Black algae is a thread-like growth that develops on rough surfaces in swimming . whether they appear on a Plaster Finish (for Concrete Pools), Vinyl Liner, or. Black algae will appear as dark black slippery spots on pool surfaces (walls and whether they appear on a Plaster Finish (for Concrete Pools), Vinyl Liner, or. Apr 13, 2018 - No one likes to see stains or discolored spots on swimming pool walls. Even if the pool water is clean, spots or stains on the wall can make . Does a plastered pool finish encourage the growth of algae, especially the dreaded black algae? NO. As anyone knows who . Modern procedures assure that the new plaster will bond to the underlying material. As with any product, there are . Aug 15, 2012 - Modern pool algae treatments can be classified into several distinct groups. . and reduce the possibility of staining to pool plaster, tile grout and . also been proven effective with strains of black algae in swimming pools. Oct 12, 2014 - If left to grow, black algae extends its roots into the plaster surrounding your pool. This can cause extensive damage to your foundation that may .