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The Home Depot

How to Get Rid of Pool Algae

Pro Referral > Home Guides > Pool and Hot Tub > How to Get Rid of Pool Algae
How to Get Rid of Pool Algae

All algae is not created equal. To prove this, we simply need to look at the four basic colors of the stuff in the pool: green, pink, yellow and black. Before you wipe them out by going to extremes and blasting the water with chlorine, let’s get to know the slime by looking at each individual algae.

  1. If you swim without fully cleaning your water toys, goggles and bathing suit after playing in the sea, you can also contaminate your pool.


    This one is very common. It’s usually discovered floating around in the pool, although green algae might cling to the walls, too. When it finds its way to the edges, it’s very slimy and grows in sheets. As this type of algae evolves, it clouds up the pool and, unchecked it will give the water a green tinge.

  2. 2.Pink

    This one is not really an algae half as much as it’s a bacteria. The pink substance finds its way to the crevasses, corners and cracks of your pool. If your pool is close to the ocean, it’s a sure bet you’ll encounter this slime. If you swim without fully cleaning your water toys, goggles and bathing suit after playing in the sea, you can also contaminate your pool.

  3. 3.Yellow

    Sometimes known as “mustard” algae, this form of gunk likes to hang around the walls of the pool. Found in the parts of the water that are in the shade, it’s not an easy algae to beat because it keeps returning to the scene of the crime. You need to handle this matter quickly and be aware that you’ll probably have to tackle this problem on a recurring basis.

  4. 4.Black

    This type of algae is the hardest one to treat of the whole bunch. It’s called black algae but it can show-up as blue, green or black spots. These penny-sized spots are almost like a tar deposit. What makes it so difficult to treat are its roots, which can infiltrate the grout and plaster. That means unless you get what you see as well as what lies beneath the surface, black algae will come back.

  5. 5.Green, Pink or Yellow Algae Solutions

    Start by scrubbing the walls of your vinyl pool with a nylon pool brush. Is the pool concrete? Use a steel brush instead. Then grab a pH test strip. You want the water to be in the sweet spot between 7.2-to-7.6. This is to ensure that when you add the chemicals, they will be at maximum efficiency.


    It’s time to give the water a blast of Dichlor. Read the directions, but here’s an approximation of what you’ll need depending on the size of your pool:


    • 2 pounds of Dichlor for pools with 10,000 gallons of water or less

    • 4 pounds of Dichlor for pools with 20,000 gallons of water

    • 6 pounds of Dichlor for pools with 30,000 gallons of water


    After the chemical has been added, run your pump for 24-hours. You don’t have to sit and watch the water churn, but you will need to backwash or clean the filter every-so-often. After 12-to-24 hours, check the water. Have things gotten dramatically better? If not, hit the pool with another treatment. You’ll need to repeat the process until the algae has been eliminated. After the slime has dropped to the bottom of the pool, vacuum it out, but try to use a device that doesn’t go directly to your filter. You don’t want to burn out the system by making the filter work too hard. Maintain the water purity by using an Algaecide every 1-to-2 weeks.

  6. 6.Black Algae Solution

    To rid your pool of black algae, you’re going to use the same process as you would with the other types of algae. The only difference is that you’ll need to scrub the spots with trichloroacetic acid or TriClor. Once finished, continue with the Dichlor treatment as you did with the green, pink or yellow algae.


    Again, follow-up is pretty much the same as before, only this time you’re going to use a black algaecide to prevent a reoccurrence. You’ll know if everything is working if you test a 1-3 ppm level of free chlorine from the water.


    Another way to measure success is by looking at your pool. If it’s at the correct pH level and it appears clear and clean, dive in. Your work is done for a couple of weeks.

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