How Do I Remove Black Algae from My Pool?

Scrub the black algae with a stiff brush, shock the pool, and maintain proper chlorine levels to prevent recurrence.

What is Black Algae?

Black algae are one of the most persistent types of algae that can grow in your pool. Unlike green or yellow algae, black algae grow in small, black patches on the pool surface, particularly in areas that are shaded or poorly circulated. Black algae are often found in cracks and crevices, making them more difficult to remove.

Causes of Black Algae Growth

Black algae thrive in pools with poor water circulation, high pH levels, and unbalanced water chemistry. Other factors contributing to black algae growth include:

• High pool temperatures

• Inadequate sanitation

• Low chlorine levels

• Lack of pool cleaning and maintenance

If any of these factors are present in your pool, they can create the perfect environment for black algae to thrive.

How to Remove Black Algae from Your Pool

Removing black algae requires a bit of effort and the right tools. You’ll need to clean the affected area thoroughly and adjust your pool’s water chemistry to prevent future growth. Here’s a step-by-step guide to removing black algae from your pool:

1. Brush the Affected Area

Before you do anything, it’s essential to scrub the black algae off the surface of your pool. Use a stiff-bristled pool brush to scrub the areas where the black algae are present. Make sure to scrub in a circular motion to dislodge the algae from cracks, tiles, and grout.

• Tip: Focus on the areas where the algae are the most stubborn, as black algae tend to grow in these places.

2. Shock the Pool

Once the algae are scrubbed off, the next step is to shock your pool with a high dose of chlorine. Pool shock is a powerful chemical that kills algae and other microorganisms. By shocking your pool, you’ll eliminate any remaining black algae spores that might be hiding in the water.

• How to Shock Your Pool:

  • Test your pool’s water to determine the current chlorine level.

  • Follow the instructions on the pool shock package for the correct amount.

  • Add the shock to your pool during the evening, as the sun can quickly degrade chlorine during the day.

  • Allow the pool pump to run overnight to circulate the shock and distribute it evenly throughout the pool.

3. Apply Algaecide

After shocking the pool, apply a quality algaecide that is specifically designed for black algae. Algaecides contain chemicals that target algae spores, preventing them from regrowing.

• Tip: Choose an algaecide that’s labeled for black algae and follow the manufacturer’s instructions closely. Apply the algaecide directly to the affected areas for better results.

4. Brush Again

Once the algaecide has been applied, go back over the affected areas with your pool brush. This helps ensure that the algaecide gets into every crevice where black algae can hide.

• Tip: Regular brushing will help break apart the algae and prevent it from regrowing.

5. Vacuum the Pool

After brushing, it’s important to vacuum your pool to remove any leftover algae debris and dead algae cells. Use your pool’s manual or automatic vacuum to clean the pool floor, walls, and waterline.

• Tip: Be sure to clean your vacuum after use to prevent any remaining algae from transferring back into the pool.

6. Test and Balance Your Pool’s Water Chemistry

Once you’ve tackled the black algae, the next step is to ensure that your pool’s water chemistry is balanced to prevent future growth. Regularly test and adjust the following levels:

• pH: Ideal range: 7.4-7.6

• Chlorine: Ideal range: 1-3 ppm (parts per million)

• Alkalinity: Ideal range: 80-120 ppm

• Calcium hardness: Ideal range: 200-400 ppm

Proper water balance helps maintain pool cleanliness and makes it more difficult for black algae to grow.

7. Clean the Pool Equipment

Lastly, ensure your pool equipment, such as filters and pumps, are free of any algae buildup. Clean the pool filter according to the manufacturer’s instructions to ensure it’s running effectively.

Preventing Black Algae from Returning

Removing black algae is only half the battle. To prevent it from coming back, it’s crucial to maintain proper pool maintenance and water chemistry. Here are some tips to help prevent black algae from growing in the future:

• Maintain Proper Chlorine Levels: Ensure that your pool has consistent chlorine levels to prevent algae growth. Test your pool water regularly to keep levels within the ideal range.

• Improve Water Circulation: Poor water circulation is a major factor in black algae growth. Ensure that your pool’s filtration system is working properly and that water is circulating efficiently throughout the pool.

• Brush Regularly: Regular brushing will help prevent algae buildup, especially in hard-to-reach areas like pool corners and seams.

• Shock Your Pool Regularly: Shocking your pool every few weeks can help prevent algae from taking hold and spreading.

• Keep Pool Surfaces Clean: Regularly clean your pool’s surfaces to remove dirt, debris, and organic material that can provide nutrients for algae.

Additional Tips for Pool Maintenance

Here are some extra tips that can help keep your pool in the best possible condition and prevent any type of algae growth:

• Keep the Pool Filter Clean: Make sure your pool filter is cleaned and replaced regularly. A clean filter helps maintain water circulation and removes particles that could promote algae growth.

• Ensure Good Pool Covering: When not in use, cover your pool to protect it from debris and prevent algae spores from entering the water.

• Monitor for Leaks: Ensure that your pool’s plumbing is in good condition. Leaks in the pool system can create areas of low water circulation, promoting algae growth.

• Use Pool Clarifiers: Pool clarifiers help clear up cloudy water, making it more difficult for algae to take hold. Use them regularly to keep your pool water sparkling clean.

Why Black Algae Is Hard to Remove

Black algae are tougher to remove than other types of pool algae because they have deep roots that embed into the pool’s surface. Unlike green or yellow algae, which are free-floating and easier to scrub away, black algae forms layers that cling to the pool's walls and grout lines.

This makes black algae more resistant to traditional pool chemicals. The key to removing it is persistence. You’ll need to shock your pool, scrub it, and apply specialized algaecides to fully address the issue.