Algae - Microscopic, plantlike organisms that contain chlorophyll.
Within the pool and spa industry, algae are typically classified into 5 basic types. 2 of these types are not actually algae at all, but other organisms.
- Green algae (chlorophyta) are often found free-floating in water, or adhering to pool walls. Chlorine can exterminate them, but some are more resistant; these may respond better to a copper algaecide.
- Yellow algae (phaeophyta) or "mustard" algae cling to pool walls and brush off easily, almost like a powder. They resist chlorine, and tend to reappear soon after brushing.
- "Black" algae (cyanophyta) is actually blue-green, and tends to appear on walls. This type is most difficult to kill, due to its chlorine resistance, strong roots, and protective mucous layer.
- Pink "algae" are actually bacteria that create a pink microbiological stain. They attach to almost any underwater surface, but can often be killed with chlorine.
- White "algae" are actually mold or fungal spores that usually appear in pools treated with biguanide (PHMB). Hydrogen peroxide is an effective treatment.
- Diagnosing Discoloration — Pool & Spa News — 4.15.2010
- Algae Altogether — Pool & Spa News — 3.13.2009
- Chemicals QMR: The Specialists — Pool & Spa News — 6.15.2004