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Kill Pool Black Algae

A lgae are plants that grow in water that is not properly sanitized and they feed on sunlight and minerals in the water. Among the existing types of algae, the hardest to get rid of is the black algae because it usually grows in colonies and unless you kill it at its root, it will continue to grow and affect your pool. What is even worse about it is the fact that it will not only appear on the bottom of the pool but also in the plaster or concrete.

In case it is not removed, the algae can seriously damage the pool, and although you may follow the right steps to sanitize it, it can still grow and develop. Therefore, in case you have noticed this appearance in your pool and you want to know the exact steps to efficiently kill black algae, read the lines below and see what you have to do to eliminate this risk.

How to Kill Black Algae in Your Swimming Pool Picture 1 Image

Maintain the Filter

Since it has made its appearance in the pool, it is also possible for it to be present in the filter, so it is recommended that you clean the filter thoroughly. Also, besides the filter, it is wise to clean the pool equipment so that any possible algae to be removed and to impede its reappearance. You should follow the steps:

  • Canister – You should empty the filter canister frequently because it fills with debris from the vacuum
  • Check Brushes – It’s important to remove any junk from the brushes, inlets, and wheels as they will negatively affect the efficiency of the operation
  • Hose – You must always store the pool cleaner hoses flat to prevent kinks and knots from developing

Brush the Affected Areas

The first step you have to take is to brush the areas affected by the black algae with the help of a brush that is specially designed for your type of pool. You have to do this to remove the protective cover of the algae so that the chemicals used can effectively destroy the roots. Therefore, you have to firmly brush the affected areas and if necessary you can repeat this procedure more than one time. However, make sure that you sterilize the brush after using it because it can easily grow on it.

Robotic pool cleaners go across the surfaces of the pool and remove the most stubborn gunk found, all without requiring your interference in the process. So, to have an easier time with pool upkeep, maybe you should get your hands on a robotic device too.

Use a Chlorine Tablet

After you finish brushing the pool, you can utilize a broken chlorine tablet and scrub all the affected areas to increase the chances of killing the unwanted mold. This procedure may require more time, but you should try to do this if you want to achieve the best results. There are several methods to do it, including:

  • Floating Chlorine Dispenser – These gadgets that vary in size travel around the pool as the tablets melt. Nevertheless, it’s very important to remember that if you have a pool liner, this isn’t the best choice for you. The dispenser might get blocked in one place and discharge all the tablets there, creating a high level of chlorine
  • Pool Skimmer – The filter allows the water to move onto the tablets, which makes them melt faster and uniformly. The disadvantage is that the tablet can dissolve even without water going over it. Thus, it can cause your equipment to get damaged
  • Chlorinated Granules – This is a convenient option since you can sprinkle it all over the pool without needing to purchase extra equipment. The only drawback with this solution is the fact that you will spend a long period to pulverize the chlorine

Learn here how to balance the water in the pool to guarantee sanitary, proper swimming conditions each time you jump into the water.

Add Algaecide

This is another significant step you have to take because although the algaecide does not harm the black algae, it helps the chlorine do its job by eliminating the protective shield of the contaminant. Therefore, add it in the areas affected by the algae, and then in the water, and let it sit overnight for the best results. You should follow these steps to make it efficient:

  • Check – Make sure that the pool’s equipment is working properly. You should also adjust the pH level if the package tells you to
  • Super Chlorinate – You should increase the level of chlorine in your pool and let it sit for up to 48 hours until it goes to a normal level. Do not forget that the chlorine level should be normal before you start!
  • Add Algaecide – Add it in compliance with the guidelines on the package. Follow those closely if you want to get rid of algae fast. You should let the pool sit overnight and vacuum it the next day

How to Kill Black Algae in Your Swimming Pool Picture 2 Image

Shock the Pool

By shocking the water you can disinfect your pool and eliminate the existing algae. The most efficient way to this is to add 3 pounds of chemicals per 10,000 gallons after the sun goes down to prevent the UV rays from altering the chemicals in the pool. After that, you have to let the treatment for 24 hours while turning the pump off. During this time, you can brush again the pool, offering special attention to the areas which were affected by the black algae. You should always shock the pool after:

  • Heavy and consistent pool use
  • Severe weather conditions such as a rainstorm or high winds
  • High water changes
  • Bowel-related accidents

Vacuum the Pool

Vacuuming the pool after the previous steps will help you perform the normal cleaning task, but it will also help you eliminate the dead algae. In this way, your pool will be clean and you will be able to eliminate any existing dead particles. To make your work less tiring, we recommend for you to invest in a robotic pool cleaner that will handle vacuuming the surfaces of the pool for you. Best of all, this type of cleaning robot can handle filtering the water of the pool as well, thus both the surfaces and the water will be clean and free of debris of all kinds. Therefore, the chances for this problem to appear will be greatly reduced. Just program it to start cleaning the pool daily, and you won’t ever have problems of this kind.

A cheaper option for vacuuming the surfaces of the pool without actually putting in effort yourself is to use one of these top-rated pool vacuum cleaners that flaunt an automatic operation.

Repeat the Process if Necessary

In case you notice that black algae are still present in the pool, it is recommended that you repeat the entire process until you achieve the desired results. As we have mentioned before, removing it is quite difficult and it usually requires more time until it is eliminated.

Don’t forget to routinely check the pool water stats using a digital water tester so that you can prevent black algae from growing ever again and becoming an issue.

Final Thoughts

Among all the contaminants that can end up in your pool, algae are the most unaesthetic. They tend to multiply at a very fast pace and take over the floor, the walls, and the waterline of the pool. Thus, the only solution is periodical cleaning and the use of chlorine to prevent the growth of algae. Moreover, after severe weather conditions or intense use of the pool, it is recommended to clean it by adding a larger quantity of chlorine. This procedure is known as the shock of the pool. Once the problem is eliminated, keep in mind that it can easily return, so use algaecide and maybe a pool robot to prevent them from invading the pool once again.

Braden Ewing
Braden Ewing
Braden is the editor-in-chief at, as well as the oldest member of the team. He has previous experience in sales as he worked at a local electronics store. While there, Brandon first encountered robotic devices for household use and become passionate about the subject. Since joining the team, he provided expertise regarding the latest technologies in the domain of automated cleaners, conducting proper research at all times to provide users with content that is relevant.

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