Common Types of Pool Algae and How To Get Rid of Them - Algae Web (2023)

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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.

(Video) How to Get Rid of POOL ALGAE (Green Water) | Swim University

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.

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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.

(Video) How to Get Rid of Green & Yellow Pool Algae│Leslie's

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.

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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.

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(Video) HOW TO Get Rid of Pool Algae For Good! // PoolRx Review // POOL SERIES

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


What kills algae immediately? ›

Chlorine is still one of the most effective killers of algae so doing a super-chlorination of 10-20 ppm of chlorine can go a long way towards wiping out the algae. Liquid chlorine is an ideal shock for algae because it is fast acting and does not add cyanuric acid (CYA) or calcium to the water.

What else kills algae in a pool? ›

4 Most Common Chemicals to Treat Pool Algae
  • Polyquats Algaecide. This chemical is ideal if you notice any discoloration on the walls of your swimming pools caused by staining algaecides. ...
  • Copper Based Algaecide. ...
  • Quaternary Algaecide. ...
  • Sodium Bromide.
Sep 9, 2020

What are the types of pool algae? ›

Of the many species of algae, only four are common in household swimming pools: green, yellow, pink, and black.
  • Green Algae. Green algae is by far the most common type of fresh water algae. ...
  • Yellow Algae. ...
  • Pink Algae. ...
  • Black Algae.

What is the most common method for treating green algae? ›

Copper Sulfate or “blue stone” is probably the most commonly used algal treatments because of its availability and low cost. Copper sulfate comes in several forms depending on how finely it is ground. Smaller crystals will dissolve easier than larger crystals.

What kills algae naturally? ›

Not only is barley straw a natural pond algae killer, but it won't harm your fish or plants – and it's cheap to buy too. In fact, I've read that barley straw is a more effective pond algae remover, and it works better to clear pond water than expensive chemicals.

How do I get rid of algae in my pool overnight? ›

Use a pool brush to vigorously scrub any pool surfaces covered in algae, including the walls, floors and steps. Apply a green algaecide according to the directions on the label. Let the water circulate for 24 hours, then brush the pool surfaces again. Vacuum or backwash to remove any remaining dead algae.

What chemical stops algae growth? ›

Chemical control

Aquatic herbicides used to treat algae are called algaecides. They're often copper-based compounds (e.g. copper sulfate, copper chelate communes, chemical Endothall). Effective if the entire surface is treated. Algaecides are expensive and need frequent dosing.

What kills algae better chlorine or algaecide? ›

Chlorine—yep, your typical sanitizer—is much more effective at killing algae than algaecide is. Even if your water gets cloudy and your walls get slimy, chlorine can still kill it. That's because chlorine oxidizes bacteria and single-celled algae, which means they trade electrons.

What are the 4 main types of algae? ›

Chlorophyta (Green algae) Rhodophyta (Red algae) Paeophyta (Brown algae) Xanthophyta (Yellow-green algae)

What are the 3 types of algae? ›

There are 3 classes of algae: Chlorophyceae, Rhodophyceae, Phaeophyceae.

Should I use shock or algaecide first? ›

While shocking and adding algaecide is effective in getting rid of algae, it should not be done together. This is because when you mix chlorine and algaecide together, it renders both of them useless. Hence, you should first shock the pool and wait for the chlorine levels to fall below 5 PPM.

Is hydrogen peroxide good for algae? ›

Hydrogen peroxide is a common treatment for algae overgrowth in backyard ponds. If you're struggling with algae, particularly string algae on rocks or waterfalls, then hydrogen peroxide could be an effective natural solution.

Why is my pool still green after shock and algaecide? ›

Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.

Can baking soda get rid of algae? ›

Only algaecides can "kill" algae in pool water. However, baking soda can help clear up algae.

What is the easiest way to clean algae? ›

Organic soap and white vinegar are particularly excellent cleaning solutions. You can use street salt or domestic salt to remove algae from the terrace or concrete floor. You can use a high-pressure spray to remove algae and other green stains.

How do you stop algae from growing? ›

Perform water changes: The single most important way to avoid algae is to perform regular water changes. Change 10 to 15 percent of your aquarium water every week to lower nutrients in the water. This will remove the nitrate that accumulates in aquariums, which is one of the main fertilizers for plants.

Does Dawn soap remove algae? ›

I've had fantastic success cleaning algae from just about every outdoor surface using liquid dish soap and my favorite exterior cleaning brush.

How much baking soda do I put in my pool to get rid of algae? ›

A rule of thumb is 1.5 lbs. of baking soda per 10,000 gallons of water will raise alkalinity by about 10 ppm. If your pool's pH tested below 7.2, add 3-4 pounds of baking soda. If you're new to adding pool chemicals, start by adding only one-half or three-fourths of the recommended amount.

Does pool Shock get rid of algae? ›

"Shocking" the pool with a large dose of chlorine is the most effective way to kill the existing algae and bring your pool back to sanitary conditions. This usually works within 1–3 days, but can take up to a week if pool conditions are poor.

How long does it take for pool to clear up after algae? ›

The only thing that kills algae is CHLORINE (or your sanitizing product, or one of the copper-based algaecides on the market). You need to raise the level of your chlorine – shock the pool – and maintain that high level until all the algae is dead. This may take 3 to 4 days.

What product gets rid of algae? ›

Wet & Forget Outdoor eliminates algae without any bleach, scrubbing or pressure washing. No matter the type of algae you have covering your outdoor surfaces, Wet & Forget Outdoor will take care of it. It penetrates black algae's defenses and removes the green algae that can grow on the shaded areas of your roof.

What color stops algae growth? ›

On the contrary, blue and red will let the light through to be photosynthesised; green will inhibit growth the best as the algae will reflect that light back instead of absorbing it. Hence the green colour of algae.

Does salt stop algae? ›

Finally, while rock salt applied at 1lb per 100 gallons will kill string algae, the resulting mass of dead and rapidly decaying vegetation will pollute your pond and cause even more problems with water quality.

What is the safest algaecide? ›

Green PondFx is the safest, most effective algaecide on the market for backyard ponds, but caution must be used when applying it during warm summer weather!

Is Vinegar a good algaecide? ›

Vinegar is acceptable to use for killing algae and cleaning a pond when it is drained. The acidic is good at lifting away the stubborn algae deposits and stains without damaging the liner material. When used in this way in limited amounts, the leftover vinegar residue won't hurt the fish or change the pH of the water.

What are 5 examples of algae? ›

Multicellular examples of algae include the giant kelp and brown algae. Unicellular examples include diatoms, Euglenophyta and Dinoflagellates.
Examples of Algae
  • Ulothrix.
  • Fucus.
  • Porphyra.
  • Spirogyra.

What are the 12 types of algae? ›

They are Chlorophyceae, Xanthophyceae, Chrysophyceae, Bacillariophyceae, Cryptophyceae, Dinophyceae, Chloromonodineae, Euglinineae, Phaeophyceae, Rhodophyceae and Myxophyceae (Cyanophyceae). The classification is published in his book titled “The Structure and Reproduction of Algae”.

What is the most popular algae? ›

Green algae, diatoms and dinoflagellates are the most well-known, though other microalgae species include coccolithophores, cryptomonads, golden algae, yellow-green algae and euglenoids 1. There are so many diatoms drifting in the oceans that their photosynthetic processes produce about half of Earth's oxygen 9.

What types of algae are harmful? ›

Red tides, blue-green algae, and cyanobacteria are examples of harmful algal blooms that can have severe impacts on human health, aquatic ecosystems, and the economy. Algal blooms can be toxic. Keep people and pets away from water that is green, scummy or smells bad.

What algae won't brush off? ›

Black Algae

If you ever had yellow algae and thought that was tough, think again. Black algae are the stinginess of all the algae, although the good thing is it's not very common. What makes this algae so hard to get rid of is the defense mechanism it processes and it's strong roots.

What kind of algae won't brush off in pool? ›

So if the pool water isn't cloudy and the 'dirt' is clinging to the walls after brushing, the problem is likely be yellow/mustard algae. Yellow/ Mustard algae is very resistant to even high chlorine levels and will grow and thrive in a chemically well-balanced pool.

Is algaecide or shock better for algae? ›

Chlorine shock is usually the best way to get rid of green algae. However, an algaecide may become necessary if you're fighting more chlorine-resistant algae, such as mustard algae or black algae. Even then, the pool algaecide should work with chlorine or other sanitizers – not as an alternative to them.

How do you get rid of algae overnight? ›

Use a pool brush to vigorously scrub any pool surfaces covered in algae, including the walls, floors and steps. Apply a green algaecide according to the directions on the label. Let the water circulate for 24 hours, then brush the pool surfaces again. Vacuum or backwash to remove any remaining dead algae.

Does hydrogen peroxide get rid of algae? ›

Hydrogen peroxide is especially effective against green algae and blue-green algae (cyanobacteria). It is heavier than water and sinks to the ground, which is useful if you're dealing with algae near the ground and somewhat of a hindrance if the algae are higher up in the tank.

Does hydrogen peroxide dissolve algae? ›

Hydrogen peroxide is a common treatment for algae overgrowth in backyard ponds. If you're struggling with algae, particularly string algae on rocks or waterfalls, then hydrogen peroxide could be an effective natural solution.

Does vinegar dissolve algae? ›

Vinegar is acceptable to use for killing algae and cleaning a pond when it is drained. The acidic is good at lifting away the stubborn algae deposits and stains without damaging the liner material. When used in this way in limited amounts, the leftover vinegar residue won't hurt the fish or change the pH of the water.

Does sunlight get rid of algae? ›

For dense cultures (Secchi Disk Depth <4cm), you can go up to full sun, if the culture can stay under 32C (90F). Light plus heat kills algae.

Does white vinegar get rid of algae? ›

Although a bleach solution or white vinegar can help kill green algae, in most cases this is not a suitable solution; the Algae can grow back very quickly.

Is vinegar better than bleach for algae? ›

In the case of algae and mold, it does a better job than bleach, and it is better in the long term for killing these infestations. Oftentimes, vinegar can be found in your home or garage. Be sure to use distilled white vinegar to clean algae from your concrete. You can also use cleaning vinegar.

What is a homemade green algae remover? ›

White distilled vinegar: White vinegar is a popular natural cleaner that can be used both inside and outside. Simply combine one gallon of water with one cup of white vinegar and scrub the deck with the solution to remove algae, mold, and mildew.


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