Black algae are single-celled organisms that grow in large colonies. They contain chlorophyll like other algae, but they also contain compounds that mask the green color. They form in cracks and crevices on pool surfaces (especially plaster finishes) and can grow somewhat protected from the surrounding environment due to the formation of a protective layer on the outside of the cell. This makes black algae more difficult to treat and it is somewhat resistant to normal chlorine levels.
To Kill Black Algae:
Use Banish® as it kills all types of swimming pool algae
Spot Kill® is specifically formulated to kill black algae on walls
Spot Kill® WP should only be used on white plaster pools.
Important Note: Brushing is extremely important when treating black algae because that protective layer has to be broken in order for the sanitizer or algicide to come in contact with the cells.
5 Steps to Prevent Algae Growth:
1. Maintain a sanitizer residual of 1-3 ppm
2. Do an initial and weekly application of a preventative algicide (such as Backup 2)
3. Shock routinely
4. Make sure there is adequate circulation and filtration