How to Remove Algae From Gunite Pools

Gunite pools are an excellent addition to any backyard. They are durable, long-lasting, and can withstand a lot of use. However, algae can quickly ruin the appearance and functionality of the pool. Algae can grow on the walls, floor, and other surfaces of the pool, making it slippery and dangerous. This article will discuss the different ways to remove algae from gunite pools and keep them clean and clear.

What is algae

Algae are tiny plants that can grow in any body of water. They thrive in warm and humid conditions, making a swimming pool the perfect place for them to grow. There are three types of algae that can grow in a swimming pool: green, black, and yellow. Green algae are the most common, and they give the pool a greenish tint. Black algae are more difficult to remove and can appear as black spots on the walls and floor of the pool. Yellow algae are the least common, and they appear as yellow spots on the walls and floor.

What causes algae to grow in a gunite pool

But, can algae stain a gunite pool? The answer is yes. Algae can stain a gunite pool. Gunite pools are known for their rough and porous surface, which makes them prone to algae growth and staining. Here are some of the common causes of algae growth in a gunite pool:

  • Poor Water Circulation: One of the main reasons for algae growth in a pool is poor water circulation. In a gunite pool, water must circulate through the filter and back out into the pool to ensure proper circulation and filtration.
  • Inadequate Sanitation: Inadequate chlorine levels or other sanitizing chemicals can contribute to algae growth in a gunite pool. Algae thrive in environments with high levels of phosphates and nitrates, which can be introduced into the pool by swimmers, rainwater, or organic debris.
  • Poor Water Chemistry: An imbalanced pool pH level can make chlorine less effective, leaving the pool water vulnerable to algae growth. A pH level of 8.0 or higher is particularly conducive to algae growth.
  • Lack of Proper Maintenance: Neglecting regular pool maintenance tasks such as brushing the pool walls and floor, and backwashing the filter can lead to the buildup of debris and organic matter that can fuel algae growth.
  • Warm Water Temperature: Warm water temperatures provide an ideal environment for algae to thrive. Gunite pools are particularly susceptible to high temperatures due to the rough texture of their surfaces, which can harbor algae spores more easily than smoother surfaces.

How to prevent algae from growing in gunite pool

Preventing algae growth in a gunite pool requires regular maintenance and careful monitoring of the pool’s chemical levels. Here are some tips:

  • Maintain Proper Water Chemistry: Algae prefer a pH level of 8.0 or higher, where chlorine is rendered less effective. It is crucial to test the pool water regularly and maintain a pH range of 7.2 to 7.6 to prevent algae growth.
  • Keep Sanitation Levels High: Regularly add the appropriate amount of chlorine to the pool water to maintain adequate sanitation levels. Inconsistent or low levels of chlorine are one of the biggest reasons for algae growth in a pool.
  • Regular Maintenance: Keep a routine maintenance schedule for cleaning and balancing the pool water. It is important to scrub the pool walls, floor, steps, and corners regularly using a pool brush. Vacuum the pool surface as thoroughly as possible, making sure to clean under stairs, along the pool wall, and on steps. It is also important to pump the water through the filter system and backwash the filter regularly to remove dead algae and debris.
  • Use Algaecide: Regular use of algaecide can help prevent algae growth in the pool water. Mustard algaecide is particularly effective in preventing and treating algae growth in gunite pools.
  • Maintain Proper Water Circulation: Proper water circulation is crucial in preventing algae growth in a pool. Run the pool pump and filter 24 hours a day to keep the water circulating constantly.

How to Remove Algae From Gunite Pools

If algae has already grown in the pool, there are several ways to remove them.

  • Brush the pool walls and surfaces thoroughly using a wire-bristle brush to remove the visible algae.
  • Vacuum the bottom and sides of the pool well to help get the algae out].
  • Use a good quality filtration system to keep the water clear. Clean the filters to remove any debris from the water.
  • Shock the pool by increasing the free chlorine levels in the pool water. You can use granulated shock that you mix with water or pre-mixed liquid shock.
  • Add algaecide according to the label directions. Allow the water to circulate for 24 hours and vacuum or backwash the pool again to remove the remaining dead algae.
  • If large amounts of algae are suspended or floating on the surface, add a flocculent to bind the particles together and make them fall to the bottom. Continue to run the filter until the algae is cleared from your pool.

Removing Green Algae

For green algae, use a pool algaecide to kill the algae. Follow the instructions on the product label, and be sure to use the correct amount for the size of your pool. Brush the walls and floor of the pool after adding the algaecide to remove any dead algae.

Removing Black Algae

Black algae are more difficult to remove and require a different approach. Use a stiff-bristled brush to scrub the algae spots and remove any dead algae. Apply a black algae treatment to the affected areas and let it sit for at least 24 hours. Brush the walls and floor of the pool again to remove any dead algae.

Removing Yellow Algae

Yellow algae are the least common but can still be challenging to remove. Use a pool algaecide specifically designed for yellow algae, following the instructions on the product label. Brush the walls and floor of the pool after adding the algaecide to remove any dead algae.


Algae growth in a gunite pools can be unsightly and dangerous. However, with proper prevention and removal techniques, you can keep your pool clean and clear all year round. Regularly maintain the water chemistry, brush the walls and floor of the pool, and run the pool filter for at least 8 hours a day. If algae do grow in the pool, shock it with chlorine and follow the appropriate treatment for the type of algae present. With a little effort, your gunite pool will be a beautiful and safe place to swim.

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