Algae that grows in swimming pools and spas, can be green, brown, yellow, black or pinkish. Most often they’re a slimy substances that resembles fur and typically grow on the steps and in corners – places where circulation may not be optimum. Most swimming pools are in the sun several hours per day, and it’s sunlight that speeds algae growth. Terrific right!
We’ve listing common algae types and colors, and recommended remedies from pool pros.
Source: The Ultimate Guide to Pool Maintenance by Terry Tamminen.
Green algae – chlorophyta – is a slimy substance that can be found on pool and spa surfaces. First signs of it will be in small clusters on pool steps or lurking in corners. It’s at this stage that you should start to attack it — green algae can grow quickly in 24 hours or less.
Brushing will remove green algae, but it won’t destroy it. Super chlorination — aka shocking or shock treatment — will sanitize pool water that might be resistant to normal chlorination. Maintaining your pool regularly during swim season is key to staying on top of a green algae outbreak.
Yellow algae also goes by the appetizing term “mustard algae” because of its brownish or muddy yellow color. While yellow algae (phaeophyta) doesn’t spread as quickly as green algae, it is harder to destroy. Like green algae, yellow algae grows in the same fur or mold-like pattern. Unlike green algae, brushing will not do much to remove it, although it will remove the top layer of slime, which exposes the algae underneath. Super chlorination and regular maintenance will help kill mustard algae.
Black or Blue-Green Algae
Black or blue-green algae are primarily found in lakes and ponds. You would only typically see it in a pool if it were not being maintained. Black algae is the pool pro’s worst nightmare. At the first sign of black algae, you need to consider the pool or spa as a patient in critical condition. Why? Unlike green or yellow algae, black algae doesn’t have and outer layer of slime, which acts as a protective barrier for the algae underneath. Black algae will penetrate deeply into hard surfaces, like plaster and concrete. It first appears as black spots and then proliferates. If you see signs of it, immediately use a stainless steel brush, which cracks the algae’s shell and allows sanitizers to penetrate it.
Pink algae is actually a fungus. It appears as a reddish slime, usually at a swimming pool’s water line. Unlike its colorful cousins, pink algae is the easiest to remove. Simple brushing and regular sanitizing will keep it under control.