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How to Kill Black Algae in Your Swimming Pool

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Black algae is perhaps the hardest algae to get rid of. It has very deep roots that can grow into the side of plaster or concrete pools. It also has many layers that protect it from normal chlorine levels. You will usually find black algae clinging to your pool walls or steps in very shady spots. So in order to get rid of this algae, you must be aggressive!

How to Kill Black Algae in Your Swimming Pool

Black algae comes from the ocean. A common way for you pool to be infected by black algae is by a bathing suit that has once been in the ocean. With that said, always wash your bathing suits after swimming. It’s just good practice.

How To Get Rid of Black Algae

Here is a step by step guide to get rid of this slimy, stubborn creature.

Warning: Be prepared to do a lot of brushing. I suggest buying a good quality pool brush If you click this link and make a purchase, we earn a commission at no additional cost to you. for this procedure.

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1. Sanitize everything.

Bathing suits, equipment, toys, and floats. Make sure you wash your bathing suits in a washing machine and dryer. This should kill the algae. Wipe down toys and floats with bleach If you click this link and make a purchase, we earn a commission at no additional cost to you. . Use a scrub brush If you click this link and make a purchase, we earn a commission at no additional cost to you. for more thorough cleaning. Keep all the maintenance equipment in the pool so that it becomes sanitized.

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2. Check the water chemistry in your pool.

Test your pool water If you click this link and make a purchase, we earn a commission at no additional cost to you. regularly to make sure your pH levels are between 7.4 and 7.6 and your alkalinity levels are between 120 and 150 ppm (parts per million).

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3. BRUSH THE HECK OUT OF YOUR POOL.

I cannot stress this enough. This will be the key to getting rid of black algae. Brush hard, brush thorough, brush often.

4. Triple shock your pool.

Add 3 pounds for every 10,000 gallons of water your pool holds. Make sure you add the pool shock If you click this link and make a purchase, we earn a commission at no additional cost to you. at night or dusk and run your filter 24 hours a day until the black algae has been taken care of.

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5. Brush your pool again and again.

Brush it the following day at least 3 or 4 times concentrating on where you first spotted the algae. Remember, black algae has deep roots that can be embedded into your pool walls. It may look like it’s gone, but it’s probably still in there. Just keep brushing.

Continue brushing for several days after the shock. I would wait about 3 days and then shock your pool again with a normal amount. 1 pound per 10,000 gallons of water. Brush your pool If you click this link and make a purchase, we earn a commission at no additional cost to you. for a few more days after that until you feel confident that the black algae is gone.

This is not a guarantee. Black algae is a bastard and could continue to infect your water. If it does, you know how to kill it, just be more aggressive next time. Perhaps an additional dose of triple shock and constant brushing.

How To Prevent Black Algae from Growing

Keeping your pool properly balanced and sanitized is the key to keeping all forms of algae from growing. Make sure you

Happy Swimming!

Recommended Reading

How to Get Rid of Algae in Your Pool
Guess what. Sanitizer isn't enough to keep algae from invading your pool. Get rid of algae and keep it from coming back so you can enjoy a clean, clear pool again.
How to Quickly Remove Pollen From Your Pool
Learn all the steps you need to quickly and easily remove pollen from your pool so your water looks crystal clear and ready for swimming.
How to Clear a Green Pool in 5 Days or Less
Do you have a green pool? With a little elbow grease (read: work) and these easy steps, you can easily clear a green pool in 5 days or less.
How to Get Rid of Mustard Algae in a Pool
Got mustard algae? Here's a very simple tutorial that will walk you through how to remove stubborn mustard algae from your swimming pool.

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Last Updated: Sunday, July 28th, 2013