Common Types of Pool Algae and How To Get Rid of Them

It is a lot of fun to have your own swimming pool where you can dive in and cool off on a hot summer day. But one thing about swimming pools that isn’t quite as fun is the sight of strains of pool algae or green pool water. 

That green color in your water or green slime on the pool walls can make your gorgeous pool smell foul, look unsightly, and can affect the way you feel about taking a swim. 

One of the first steps for treating your pool algae attack is by identifying the types of pool algae you have. Once you know what type you have, you can find the right treatments and restore your pool to its former crisp blue glory. 

What is Pool Algae?

Most people believe that algae are a type of aquatic plant because it is mostly green, appears to grow and some varieties can bloom. But these types of growths are actually an organism that is found in all types of water bodies on earth. The photosynthetic eukaryotic organism group is quite diverse with over 200,000 species of algae. 

As with other organisms, these species require nutrients from water sources to the surface. They also flourish and grow rapidly when they have plenty of sunlight but some species of algae can grow in extremely cold temperatures and in limited light conditions. 

Only three of these species are commonly found in swimming pools; Green algae, black algae, and yellow or mustard algae. 

What Are The Different Types of Pool Algae

Out of all the many types of algae found in the world, you are most likely to encounter three species; green algae, yellow algae, and black algae.  The spores can be brought into your pool through wind, rain, contaminated swimsuits pool cleaning tools, and through your water supply. Once inside your pool, it will continue to grow and will flourish unless you apply the correct pool treatments. 

Here is a quick look at the most common pool algae types you will need to look out for. 

Green Algae

Green algae is the most common algae species found in swimming pools and on spa surface. There are about 22,000 species of green algae found on earth. 

This common form of algae will first form small clusters on the pool steps, on pool toys, or in the corners of your pool. The organisms flourish in pools that lack proper sanitization and filtration or that have high pH levels. If green algae are left untreated they will quickly grow and can make your entire pool appear green within days. It is best to start treating your pool the moment you notice green slime or a green tone to your pool water. 

Brushing at green algae can help loosen the deposits from your pool surface so your pool filtration system can suck up the growths. But it won’t solve your problem for good. When you brush the algae from your pool surfaces, it will break up into tiny pieces and plenty of microscopic algae spores will stay in the water and will soon resurface in different places.

The best way to treat this swimming pool algae color after brushing it from the pool surfaces is with a super chlorination product or a dose of pool shock.

You can then keep this common type of algae from forming again by monitoring and regulating your pool’s pH levels and by installing a proper filtration system that will circulate the water.  A pH level of about 7.8 is ideal for keeping green algae from growing in your pool. 

Yellow Algae

Yellow algae (Phaeophyta)are also commonly known as mustard algae because it has a muddy and yellow appearance. These organisms do not grow or spread as fast as green algae varieties but they can be harder to destroy or clear from your pool.

Mustard algae can resemble dirt or sand on the bottom of the sides of your pool. The organisms will grow in a mold-like pattern and will continue to multiply and spread on your pool surfaces.  

You can brush yellow algae from the surfaces but brushing won’t do much for removing these growths. Brushing will only remove the top layer of slime that forms on the algae which will expose the algae underneath. 

Mustard algae tend to be resilient to pool shock treatments and pool chemicals because the organisms contain compounds that defend against oxidation pool treatment products. This defense mechanism can help the algae survive and grow even in highly chlorinated conditions. 

To effectively remove and clear yellow color algae from your pool, swimming pool owners will need to create a pH level of 7.8 and chlorine level to 2-3ppm. Add a dose of granular pool shock treatment and brush your pool bottom and sides thoroughly. Your pool water needs to circulate and you need to run the effective pool filters to vacuum the debris from your pool. This step needs to be repeated daily until your pool clears up. 

It might take a few days of regular maintenance and care before the algae will be completely cleared from your pool after which you can return to your normal pool maintenance schedule. 

Black Algae

Black algae is the most resistant and hard-to-kill algae strain found in pools because it creates a protective layer that shields the algae from the pool cleaners.

This type of algae in pools starts as small black dots the size of pinheads on the pool walls. These small dots will then start to grow and will also multiply across the pool floor and walls. The types of swimming pools with rough or porous pool walls like concrete, plastered or gunite is especially vulnerable to black algae since these organisms will grab hold of the wall and penetrate the surface. Over time, this type of pool algae will develop into a heavy slime layer that makes this type of organism resilient against chlorine and oxidization pool treatments. 

Black algae spots can make your pool look unsightly but won’t alter the appearance of your pool water. These growths can’t harm your health but they can attract insects or harmful bacteria that can be dangerous to your health. Black algae can also result in bad odors in your pool. 

To get rid of black swimming pool algae, a pool owner will need to create a pH level of  7.4 – 7.6 and raise the alkalinity to 80-120 ppm. Next, you will need to brush the black spots using a pool brush. After brushing, you will need to add Black Algaecide to a bucket of water and pour it away from your pool sides. Run your poo filter more frequently to clear out the loose debris. Daily brushing is also needed as the spots reappear until the dead algae have been completely cleared from your pool. 

Pink Algae

Pink algae aren’t quite as common as green, black, or yellow algae. But this slimy bacterial matter can sometimes grow in pools. Pink slime isn’t really classified as algae since it is a bacterium. The pink color you see is pigmenting within its cells and this type of bacteria creates a slime around the bacteria to protect it. 

This type of bacteria isn’t toxic to your body but it can be unsightly and the slimy texture is offputting. 

The best way to get rid of this fungus is by preventing it from forming, to begin with. By brushing your pool surfaces weekly, exposing your pool to sunlight (pink algae flourishes in dark conditions), and maintaining the right pH levels, you should be able to keep this type of algae out of your water. 

If you do notice pink fungal growth in your pool, you should clean your pool filter and circulate the water while running the filtration system. Restore your pool to its normal chlorine levels and give your pool shock treatment. You can then brush the pool surfaces to clear off slime and growth. 

Blue-Green Algae

Blue-green algae (cyanobacteria) isn’t really an algae species. Instead, it is a bacteria that is found in many water bodies. Black algae particles can multiply rapidly during warmer temperatures. This fungus can look like scum on the water surface with a blue-green or greenish-brown hue.

This is one of the most dangerous algae species because some varieties can start to produce toxins when the growths bloom. These toxins can linger in the water for many months and have been known to result in livestock deaths.  Blue-green algae are known to create skin irritations, skin rashes, a sore throat, sore and red eyes, lip swelling, and hay fever symptoms if you swim in it. People who drink contaminated water with this bacteria can experience headaches, diarrhea, weakness, liver damage, fever, nausea, muscle, and joint pain, and cramps.

This type of algae is not very common in swimming pools and it will only start to grow if your pool is extremely neglected. Pools that have been left standing without any circulation or filtration for months can become an ideal habitat for this type of bacteria.

The bacteria is quite vulnerable to shock treatments and chlorinated products. To clear this bacteria from your pool, you can apply a shock treatment or pool algaecide and create the needed pH balance. You should also scrub your pool surfaces and create pool circulation while you run your filtration system. Clean your filters regularly so they don’t become clogged up.

If the algae growth did manage to bloom then it might be better to empty out your pool and deep clean and wash the walls before adding fresh water. 

Final Thoughts

Algae isn’t always fun to deal with but there is a good way to deal with any type of pool algae as long as you invest in the right products and regularly clean and maintain your pool. We do hope that this guide helped you identify the type of algae you have so you can treat your pool accordingly. If you want to find out more about algae and the best pool algae removal products then you should have a look at our other sites. On AlgalWeb, we offer great advice to treat and maintain any type of water body.