It’s bad enough to know your pool has traces of green algae all over it. But that’s not an issue because it’s easy to clean off. However, when you discover that your pool is infected with black algae, know that there’s a real problem and you’re about to do some real work because you have to put in the effort to get your pool all cleaned up and back to its normal state.

What does black algae look like?
Unlike its green counterpart, black algae, is a bacteria known as a cyanobacterium which is where the black name is derived from because it is blue-green in color. These cyanobacteria contain chlorophyll which aids in maintaining its color and also other water-soluble pigments that combine with its blue-green pigment to make the bacteria black.
These algae strains are super resistant and hard to kill totally off your pool. These algae strains appear all over your pool in the form of small black dots the size of a pinhead. They develop a hard outer shell that acts as a protection to the living cells of the algae. You can find this organism specifically in a pool with porous surfaces such as gunite, concrete, and the likes because these are where they can penetrate and expand their tentacles, grabbing the walls of the pool firmly. It is quite hard to get rid of this bacteria but it’s not impossible.
Why you have black algae in your pool?
The most likely way to get black algae in your pool is when you or another person uses a swimsuit used to swim in a natural body of water to swim in your pool without prior washing. This is the easiest way to move such organisms. Sometimes you may have washed the swimsuit but not properly this can also cause a spread of these bacteria. They can also get into your pool from airborne spores but the chances of this happening are very slim.
Can Black algae be harmful?
Yes. The blue-green algae can be harmful because a spread of cyanobacteria in water is known to kill every organism and animal that lives in that body of water by blocking off oxygen, sunlight, and any other nutrient needed by the organisms and animals in the water. But this is not a cause for an alarm by a pool owner.
However, they create cyanotoxins which are among the most powerful poisons in the world. If such poisons are released into your pool, they can damage you and anyone who uses the pool especially if you mistakenly swallow the pool water. You can suffer from stomach cramps, nausea, or liver damage. So you need to be on the lookout especially if you have pets and kids around the house.
How to get rid of black algae in a pool
By now you may have seen these algae in your pool and be wondering how to remove black algae from the pool. Well, I would answer this in a few steps below but you have to remember I earlier said it would require some effort. So get ready. To remove the black algae from your pool will require the use of an algaecide. The algaecide will kill the algae and make the pool wall clean. But to kill the algaecide, you need a chemical that will break the outer shell so the chemicals can kill the cell inside. You also require a pool brush to steel bristles to scrub the algae off the surface. Follow these steps to get rid of the black algae in a pool.
- Test the water and ensure the pH level of the pool ranges between 7.4 – 7.6 and its alkalinity falls within 80-120ppm.
- Scrub the walls with your steel brush to open up the algae. If you have a fiberglass, painted, or vinyl pool wall, use a nylon brush.
- Add 1.5 quarts of whatever chemical you decide to use to kill the cell of the algae per 10000 gallons.
- Mix your algaecide properly in a bucket of water and pour 12 oz. of the algaecide per 10000 gallons, let it sit for a while before scrubbing the walls again.
- Rinse the pool walls and run the water till the water wipes off the rinsed spot clean.
- Test your pool’s pH and alkalinity level and ensure they’re back to normal then put on your filter
- You can get in touch with an expert if the case becomes severe or you repeat the process and increase the amount of algaecide used.
Conclusion
While using your pool, always lookout for a return of the black algae because it is rumored that they’re likely to come back after an outbreak. Always keep an algaecide handy to keep your pool algae free. Pour the algaecide on a weekly basis inside your pool to keep it algae free.