How to Remove Algae Stains from Pool Walls

For pool owners, maintaining a clean and inviting swimming pool is a top priority. However, despite regular cleaning and chemical treatment, algae stains can stubbornly cling to the pool walls, leaving unsightly blemishes and compromising the overall aesthetics of your backyard oasis. These pesky stains are not only an eyesore but can also harbor bacteria and potentially lead to more significant algae growth if left unchecked.

If you’re struggling with algae stains in your pool, fear not! This comprehensive guide will provide you with tried-and-true methods to effectively remove those stubborn stains and restore your pool’s pristine appearance.

How to Remove Algae Stains from Pool Walls

Algae Stains: Why They Form and Why They’re Challenging to Remove

Before diving into the removal techniques, it’s essential to understand what causes algae stains and why they can be so difficult to eliminate. Algae stains are typically caused by microscopic algae that thrive in warm, moist environments like swimming pools. These tiny organisms can quickly multiply and form colonies, clinging to the pool’s surfaces and leaving behind a greenish-brown or black discoloration.

The challenge in removing algae stains lies in their resilient nature. Algae have a protective outer layer that makes them resistant to standard pool chemicals and brushing. Additionally, the porous surface of pool walls can allow the stains to penetrate deeper, making them even harder to remove.

Types of Algae Commonly Found in Swimming Pools

There are several types of algae that can potentially cause staining in swimming pools. Understanding the different types can help you better target your removal efforts:

  1. Green Algae: This is the most common type of algae found in pools. It typically appears as a greenish-blue or bright green discoloration on the pool surfaces.
  2. Mustard Algae: Also known as yellow algae, this type appears as yellowish-brown or mustard-colored stains on the pool walls and floor.
  3. Black Algae: One of the most stubborn and challenging types to remove, black algae forms dark spots or streaks that can penetrate deep into the pool’s surface.
  4. Pink Algae: While less common, pink algae can leave behind reddish-pink stains and slime on the pool surfaces.

Each type of algae may require slightly different approaches or specialized products for effective removal.

Method 1: The Power of Pool Brushes and Elbow Grease

One of the most straightforward and cost-effective methods for removing algae stains is good old-fashioned scrubbing with a sturdy pool brush. This approach works best when the stains are relatively fresh and have not had time to set in deeply.

Here’s how to tackle algae stains with a pool brush:

  1. Start by brushing the stained areas vigorously with a stiff-bristled pool brush. Applying firm pressure and using a circular motion can help dislodge the algae and break down the stains.
  2. If the stains are particularly stubborn, you can try using a brush with a more abrasive surface, like a nylon or stainless steel brush. However, be cautious with abrasive brushes, as they can potentially damage the pool’s surface if used too aggressively.
    • For concrete or gunite pools, consider using a wire brush specifically designed for removing algae stains.
    • For fiberglass or vinyl liner pools, opt for a nylon brush or non-abrasive pad to avoid damaging the surface.
  3. For added cleaning power, mix a solution of pool chlorine or trisodium phosphate (TSP) with water, following the manufacturer’s instructions. Apply the solution to the stained areas and let it sit for a few minutes before scrubbing.
    • For chlorine solutions, aim for a concentration of 10-20 parts per million (ppm) for effective stain removal.
    • TSP solutions should be mixed at a ratio of 1/4 cup TSP per 1 gallon of water.
  4. Rinse the treated areas thoroughly with clean water to remove any loosened algae and cleaning solution residue.

While this method requires some elbow grease, it can be an effective way to tackle minor to moderate algae stains without resorting to harsher chemicals or professional services.

Method 2: Harnessing the Power of Pool Chemicals

For more stubborn and deep-seated algae stains, you may need to enlist the help of specialized pool chemicals. These chemicals are designed to break down and remove various types of stains, including those caused by algae.

Here are some popular chemical options for tackling algae stains:

  1. Chlorine Shock Treatment: Shocking your pool with a high dose of chlorine can help kill and remove algae, as well as loosen and bleach stubborn stains. Follow the manufacturer’s instructions carefully and ensure proper ventilation when using chlorine products.
    • Recommended chlorine shock treatment levels range from 10-30 ppm, depending on the severity of the algae problem.
    • Popular chlorine shock products include calcium hypochlorite and sodium dichlor.
  2. Algaecides: These specialized chemicals are formulated to kill and prevent the growth of algae in swimming pools. Look for products containing active ingredients like copper compounds or quaternary ammonium compounds (quats).
  3. Stain Removers: Many pool supply stores offer specific stain removal products designed to tackle various types of stains, including those caused by algae. These products often contain oxalic acid or other powerful cleaning agents that can effectively break down and lift stains.

When using chemical treatments, it’s crucial to follow the product instructions carefully and take appropriate safety precautions, such as wearing protective gear and ensuring proper ventilation.

Method 3: Embrace the Power of Abrasives and Pumice Stones

For extremely stubborn and ingrained algae stains, you may need to turn to more abrasive methods. While these techniques require extra care to avoid damaging the pool surface, they can be effective in removing even the most persistent stains.

  1. Pumice Stones: These natural, porous volcanic rocks can be used to gently abrade and scrub away algae stains. Start by wetting the pumice stone and the stained area, then gently rub the stone over the stain using a circular motion. Rinse frequently to remove any loosened debris.
  2. Abrasive Pads or Cloths: Heavy-duty abrasive pads or cloths, like those used for scouring pots and pans, can be effective in removing stubborn algae stains. Wet the pad or cloth and gently scrub the stained area, applying moderate pressure as needed.
    • Consider using melamine foam pads, which are highly effective at lifting stains without scratching surfaces.
  3. Acid Washing: In extreme cases, an acid wash may be necessary to remove deep-set algae stains. This process involves applying a diluted acid solution (such as muriatic acid) to the stained areas and letting it dwell for a specified time before rinsing. Acid washing should only be performed by trained professionals, as improper handling can be hazardous and damage the pool surface.

When using abrasive methods, it’s essential to exercise caution and avoid excessive scrubbing or pressure, as this can potentially scratch or damage the pool’s surface. Always test a small, inconspious area first to ensure the technique is safe for your pool’s material.

Method 4: Seek Professional Assistance for Severe Cases

If you’ve tried various methods and the algae stains remain stubbornly present, it may be time to seek professional assistance. Pool service companies have access to specialized equipment and techniques that can effectively remove even the most challenging stains.

Professional pool companies may employ methods such as:

  1. High-Pressure Cleaning: Using specialized high-pressure water jets or sandblasting equipment, professionals can effectively blast away algae stains without damaging the pool surface.
  2. Acid Washing and Resurfacing: In extreme cases where the stains have penetrated deeply into the pool surface, professionals may recommend an acid wash followed by resurfacing or refinishing the affected areas.
  3. Specialized Stain Removal Products: Professional pool companies often have access to industrial-grade stain removal products and chemicals that are not available to consumers.

While seeking professional assistance can be more costly than DIY methods, it can save you significant time and effort, especially for severe and widespread algae staining. Additionally, professionals have the expertise to ensure the job is done safely and effectively, without risking damage to your pool.

Preventing Future Algae Stains: Maintenance Tips

Once you’ve successfully removed the algae stains from your pool walls, it’s essential to implement proper maintenance practices to prevent future staining and promote a clean, healthy swimming environment.

  1. Maintain Proper Chemical Balance: Regularly test and adjust your pool’s chemical levels, including chlorine, pH, and alkalinity. Imbalanced chemicals can create an environment conducive to algae growth and staining.
    • Ideal pool chemistry levels:
      • pH: 7.2 – 7.8
      • Free Chlorine: 1 – 3 ppm
      • Total Alkalinity: 80 – 120 ppm
  2. Brush and Vacuum Regularly: Frequent brushing and vacuuming can help dislodge algae spores and prevent them from settling and forming stains on your pool’s surfaces.
    • Brush at least twice a week, focusing on the walls, floor, and steps.
    • Vacuum the pool weekly to remove any settled debris.
  3. Run the Filter Efficiently: Ensure your pool’s filtration system is functioning correctly and running for the recommended duration each day. Proper filtration helps remove algae and debris from the water.
    • Most residential pools should run the filter for 8-12 hours per day.
    • Clean or replace the filter cartridge or media as needed, following the manufacturer’s recommendations.
  4. Shock Treatment: Periodically shocking your pool with a high dose of chlorine can help kill any lingering algae and prevent it from taking hold.
    • Shock the pool weekly during peak swimming season, or at least once a month during cooler months.
  5. Use Algaecides: Consider adding a preventative algaecide product to your pool maintenance routine, following the manufacturer’s instructions carefully.
    • Algaecides can be added weekly or bi-weekly, depending on the product and your pool’s specific needs.
  6. Cover the Pool: When not in use, keep your pool covered to minimize exposure to sunlight, which can promote algae growth.

By following these preventative measures and staying vigilant with regular pool maintenance, you can significantly reduce the likelihood of future algae stains and enjoy a crystal-clear swimming experience all season long.

Additional Resources and Expert Tips

For more in-depth information and expert advice on removing algae stains and maintaining a clean pool, check out these additional resources:

Remember, seeking professional assistance from a reputable pool service company is always an option for severe or persistent algae staining issues. They have the expertise and specialized equipment to tackle even the toughest stains effectively.


Dealing with algae stains in your pool can be frustrating, but with the right techniques and persistence, you can effectively remove these unsightly blemishes and restore your pool’s sparkling appearance. From scrubbing and chemical treatments to abrasive methods and professional assistance, this guide has provided you with a comprehensive overview of the various approaches to tackle algae stains.

Remember, prevention is key when it comes to maintaining a clean and inviting pool. By implementing proper chemical balance, filtration, and regular maintenance routines, you can create an environment that is less conducive to algae growth and staining.

So, whether you’re a seasoned pool owner or a new homeowner embarking on your first pool maintenance journey, arm yourself with the knowledge and techniques outlined in this article, and enjoy a refreshing and aesthetically pleasing swimming experience all season long.

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As the founder of Clean It Spotless, I am Melissa Walker, a leading expert in removing tough stains from fabrics, carpets, and upholstery. With over 10 years of experience in the cleaning industry, I have developed my own natural, non-toxic stain-fighting formulas that lift stains while preserving the integrity of the underlying material. My stain removal tutorials are widely read online, and I have appeared on local TV segments demonstrating my techniques. I also present popular stain removal workshops at community centers and schools.

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