Black Algae in Your Pool

Can you imagine how disgusting it will be when you discover black algae infecting your pool? The only word from your mouth would be “Yuck.” Luckily, it is possible to get rid of black algae. All you have to do is some work to kick out that substance from your pool. 

But first, you must know about algae and the probable reasons why it grows. So, here’s what your need to know about the microbe. 

What Are Black Algae? 

Just like all other aquatic plants, algae need water to survive. It belongs to a group of single-celled organisms that has a vast family tree. You can distinguish black algae from its other variants just by noticing its color. 

Green algae have chlorophyll that helps them maintain the green color. Besides keeping their color, chlorophyll also allows them to prepare food by photosynthesis. So, all they need to survive is carbon dioxide, sunlight, and water. 

But black algae are not like their sibling, the green algae. You can call black algae bacteria-rich, most scientists like to say. To be specific, you can call it cyanobacteria, just like the blue-green algae. 

You might wonder why black algae are black when it is closely associated with blue-green algae? Well, it is because black algae chlorophyll, along with other pigments, makes the bacteria black. In simple words, these pigments are more dominant than chlorophyll.

Can Black Algae Cause Health Hazards? 

You should be concerned about the harmfulness of black algae. So, can black algae cause health hazards? Well, the answer is entirely conditional. Since scientists classified black algae as bacteria, you should inspect the pool before diving into it. 

Yes, black algae can cause the same health hazards as blue-green algae. Black algae grow in stagnant and turbulent water bodies. It restricts the growth of other microbes by increasing the BOD (Biological Oxygen Demand) of the water body. 

Black algae also restrict sunlight by absorbing it, which makes photosynthesis impossible for other plants. However, the good news is that you won’t have to worry about these aspects. 

But what you need to worry about is cyanotoxins. Cyanotoxins are the harmful organic poisons released by Black algae. It has the potential to make you or your pets very sick. 

Black algae can cause mild health hazards when you are exposed to the infected water. For example, swimming in a pool infected by black algae can cause skin infections and prolonged irritation. But, if the Cyanotoxins make their way inside your system, you’ll visit a doctor soon. 

If you accidentally ingest this infected water, you could suffer from diarrhea, nausea, and stomach cramps. Some cases are so severe that individuals suffer from liver failure.

Besides yourself, you should take preventive measures for your pets as well.

If your dog likes to dive in the pool, keep him away from the infected waters. Therefore, take the first step, and inspect your pool regularly to prevent black algae. 

Some Tips to Spot Black Algae in Your Pool 

The part of algae that can cause problematic consequences for you is cyanobacteria. First, you must know about the appearance of black algae. These aquatic plants look like mold and are very hard to get rid of. 

If you notice anything, such as black dots or patches in your swimming pool, be careful. You might see blue-green patches as black in some black algae, and blue-green algae belong to the same family. At that period, you must realize that your pool needs to be sanitized. 

Black algae have hooks and suckers attached at their bottom. It helps them to stay attached to any solid surface, even in turbulent waters. The surface area of black algae is porous, which latches on plaster and concrete of your pool. 

The hooks and suckers release chemicals that help the plant to grow roots. So, to spot them, you can check on the concrete walls and bottom of your pool. These organisms don’t survive on the water, but they are a medium for reproduction. 

You can check in those areas of your pool where the surface is rough and not plastered. It is because the hooks and suckers of black algae find a rough surface very easy to hold. Therefore, you have to inspect every corner of your pool to spot black algae. 

Some Useful Products to GettingIt has Rid of Black Algae 

#1 Essential Values Ph Increaser

The Essential Values pH increaser is undoubtedly one of the best pH increasers in the market. It is a fast-acting inorganic substance you can use to regulate the pH levels of your swimming pool. The package contains pH increasers of 2.5 lbs. You can use one bottle for 25,000 gallons of water. 

Moreover, the Essential Values pH increasers are affordable and have a remarkable reputation in the market. But, if your pool has a capacity of more than 25,000 gallons, you have to buy more units. The main component of this pH increaser is Sodium Carbonate (Soda Ash) which neutralizes water acidity and increasing pH levels. 


  • Easy to apply on swimming pools.
  • Safe to use 
  • It has a portable package 


  • Neutralizes the effect of Chlorine 

#2 Poolmaster 20183 Stainless Steel Pool Brush 

If you want a swimming pool to sparkle and be free from black algae, you will need a pool brush. For this intention, the Poolmaster 20183 Stainless Steel Pool Brush will be the right option for you. It is specially designed for all-season use, as the company uses high-quality stainless steel to produce this pool brush.

If your swimming pool has a hard-surface finish, use the Poolmaster 20183 Stainless Steel Pool Brush. The back body of the brush is forced from casted aluminum for better handling. With superior strength, you can use this brush to clean surface angles with ease. 


  • Has a durable and sturdy design 
  • Has longer durability 
  • Better flexibility 


  • Lacks curved edges 

Tips for Getting Rid of Black Algae 

Unlike the green algae, it is more complex to get rid of the black algae. It is because the former is just a plant, but you are dealing with bacteria. These are stubborn organisms that make you worry about your pool. 

However, you can get rid of black algae just by taking a few steps and having patience. 

Step 1: Filter Cleaning 

If black algae infect your swimming pool, there are chances of algae growth in your filter. If these bacteria heavily contaminate your swimming pool, cleaning it with plain water won’t help. For better results, you can use a filter cleaner to get rid of the algae growth in your filter.

But, if there is a mild infection, you can just rinse the filter with plain water extensively.

However, if you have any problem getting rid of the algae growth in your filter, get a new one. Sometimes it is better to have a new set of parts for a smooth going. Besides, if you cannot disinfect your filter correctly, all your efforts will be in vain. 

Step 2: Inspecting the Water Quality 

The next step is to inspect the water quality with utmost observation. Inspecting the water quality will give you an estimate of the required pool shock. There are different test kits available which you can use for your inspection. 

Remember only to inspect aspects like alkalinity and pH, and don’t focus on calcium hardness. Doing such will make things more complex for you unnecessarily. Check whether the alkalinity levels of your swimming pool are between 100-150 ppm. Also, regulate the pH levels and try to keep them between 7.4-7.6. 

Besides alkalinity and pH levels, it is also necessary to check the chlorine levels. For any sanitizer you use, adjust the overall chlorine level from 1-3 ppm. If any of these parameters are not within the limit, know that the infection is multiplying. 

Step 3: Brushing the Pool 

Brushing your swimming pool is not as simple as it sounds. It is the step that requires your most manual efforts. Before brushing your swimming pools, keep in mind that it is an infection. Brush such that all black algae must feel the pain. 

If there is a stubborn black algae infection, the regular pool brushes don’t work. Because black algae have hooks and suckers at the bottom, they keep them attached to the surface. Unlike cleaning chlorine, you need more momentum to remove the black algae. 

For this purpose, stainless steel brushes will be the right option to choose. You can find countless stainless-steel brushes online or at your nearby retailer. The stainless-steel bristles embedded on the bottom of the brush will detach the algae from the surface.

After the detachment, the algae fall into the water, making it vulnerable to pool shocks. So, brush all the possible corners with the help of a flexible brush.

Step 4: Scrubbing the Spots 

Besides brushing your swimming pool, it is also necessary that you scrub the black algae spots. Because you may not be able to remove all the black algae. Even if you remove large black algae bodies, there are some remaining black spots. 

These spots are small critical areas where the infections are more concentrated. Brushing with a stainless-steel brush might be futile in removing the spots. This is when scrubbing shows its effectiveness. 

Before scrubbing those black spots, add a bit of undiluted chlorine on the spot surface. It helps to kill the bacteria and neutralize the cyanotoxins on the surface. Undiluted chlorine might cause skin irritation. Therefore, put your gloves on before scrubbing the spots.

Step 5: Shocking the Pool 

Till now, you might be familiar with the idea that black algae are one of the most stubborn bacteria. Therefore, simple scrubbing and brushing alone I want help you get rid of black algae. It is because black algae use water as a medium for their asexual reproduction. 

In this complicated case, shocking the pool four times will help you in your task. However, it is necessary to follow the company’s instructions to know the correct dose. Keep all the tools you’ve used aside to sanitize. 

Shocking your pool during the day isn’t a good idea. It is because sunlight will react with chlorine to give rise to free chlorine radicals. Since free chlorine radicals have sanitization power, the algae will survive.  

There are many pool shocking reagents available in the market. However, the best of them is calcium hypochlorite. No pool shocking reagent is more effective than calcium hypochlorite. 

Step 6: Turning the Pump ON 

To yield the benefits of shock pumping, you must turn the pump on for at least 24 hours. On then, the pool shock can show its full effectiveness. Soon, the clear water turns cloudy and turns into a colloidal solution. 

However, don’t worry; this won’t infect your filter you sanitized some time ago. Even if anything does enter, it will be dead black algae. But, if you don’t want to take any chances, you can clear your filter again. 


After reading about black algae in detail, you might think the cleaning procedure to be complex. The first step you must take to maintain your safety is to wear your swimming costume. Put on your swimming goggles to keep your eyes safe from irritation-causing microbes. 

After getting rid of black algae, it’s time to prevent it. Prevention will save you a lot of time, money, and energy to keep your pool free from microbes. You can purchase a spray that contains bleach to sanitize the walls of your pool. 

Sanitize your pool regularly to keep these stubborn bacteria at bay. Also, you must keep the parameters such as chlorine levels, pH, and alkaline measurements within the limit. If you find any algae bloom in your swimming pool, restrict the entry of your pets into your waters. 

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