What type of algae can penetrate into the plaster of the pool surface and cause damage?

Black algae is particularly notorious for its ability to penetrate into the plaster surfaces of pools. This type of algae has deep root systems that can attach firmly to the substrate, making it difficult to remove and leading to damage if not addressed. The presence of black algae can not only lead to surface staining but can also cause deterioration of the plaster over time.

While green algae can accumulate on surfaces, it typically does not penetrate or damage plaster as deeply as black algae does. Purple algae is more of a term used occasionally in reference to red or pink slime, which is caused by a different type of bacteria rather than algae itself and typically does not penetrate pool surfaces in the same manner.

Thus, the understanding that black algae has a unique ability to infiltrate and harm the plaster underlines why the option indicating all types of algae as potentially damaging is correct. Knowing this distinction highlights the importance of identifying the type of algae present and selecting appropriate treatment strategies to protect the pool surfaces effectively.