Cleaning and Preventing Pool Algae Infestations: A Complete Guide

This is a comprehensive guide to how to prevent and clean up pool algae infestations. It includes step-by-step guides on how to prevent algae from growing in the first place and how to treat it once it’s already there.

Algae and other microscopic organisms can grow in pools due to several factors, including poorly maintained pool water.

Do you want your pool to stay healthy and sparkling all summer long? We’ve shared some steps below for how to prevent pool algae from growing. 

Whether you’re a swimmer or just enjoy a cool dip in your backyard, these preventative measures will keep your swimming area pristine blue not only in summer but throughout the year!

What Are Algae?

Algae is a green, slimy, microscopic plant that can grow in pools for many reasons. Anything from algae blooms in the water to pools with poor routine maintenance can be sources of algae.

Algae are always present in pool water, even pristine blue pools, typically in small amounts that are hard to see. Pool algae are eagerly awaiting the right conditions to bloom. And when the chlorine level drops and the pH level increases, or when the pump or filter is not functioning correctly, they explode.

A swimming pool needs to be well maintained so that it doesn’t turn into an algae soup. Algae need three things: light, carbon dioxide (CO2), and the right pH level. For the most part, they require all three – so if you see green slime on your pool walls or floor, you probably have a pool algae problem!

Algae need nourishment to live. Swimming pools provide plenty of delicious food for algae to feast on. In fact, algae can eat up your swimming water treatment chemicals in just a few days! 

Problems That Pool Algae Can Cause

Pool algae can cause several problems for pool owners. The most common are the unsightly green slime on the walls and floor, which can hide many other pool problems like clogged filters, low pH, high chlorine levels, and poor contaminated water circulation. 

But pool algae are more than just unsightly; it’s destructive as well! Persistent algae in pools can consume your swimming water treatment chemicals quickly and eat up the surface of your pool, causing uneven wear and tear, and leading to costly repairs or even skimmer replacement. 

Here are some problems that pool algae can cause:

Filter Damage

Pool Algae: Filter Damage

Pool algae can clog the filter. In some cases, this can cause the pool’s filter to break down. 

Some people believe that algae are benign and harmless, but it is not so innocent. Pool algae can plug up the filter in your pool which will reduce the efficiency of your filtration system. It could also consume too much of your chlorine levels, making you sick with respiratory problems such as bronchitis or pneumonia.

A common pool algae problem is a buildup of algae on the filter. This often causes cloudy water, and it will also make it more difficult for you to maintain your chlorine levels.

Ultimately, algae are destructive and should be avoided so that you can keep your pool as healthy as possible.

What Are the Types of Algae That Can Grow in Your Pool?

Pool algae can be one of the more challenging types of contamination to deal with in your pool, as it can present itself in multiple forms and colors. Three main types of algae grow profusely in pools: cyanobacteria (blue-green algae), black algae, and green algae.

The type of procedure you undertake will vary depending on which type is growing in your pool water.

1. Blue-Green Algae

Blue-green algae are most commonly found in stagnant, still, nutrient-rich waters. To remove this form of pool algae, you will need to decrease the concentration of nutrients in your pool water.

You can do this by adding chlorine or bromine and/or removing debris from the pool bottom.

2. Black Algae

Pool Algae: Black Algae

Black algae do not have a defined color and are typically found in cool, clear water. Generally, it is caused by the rise of phosphates in your pool’s water when using shock treatment medications.

To remove black algae, you must lower the pH level of your pool’s water.

3. Green Algae

Pool Algae: Green Algae

Green algae can be found all over your pool floor and walls during the summer months when you have more sunlight streaming into your pool.

It can also appear on the surface as scum or film that turns brownish-green as it continues to grow over time (this film may even protect green algae from chlorine). 

Ways to get rid of Pool Algae Fast

Here are some methods to clear these three types of pool algae. 

1. Vacuum Your Pool Regularly

Pool Algae: Pool vacuum

Picking up the pool algae by vacuuming it leaves it in the water for only a short time and keeps it from reappearing. So, vacuuming must be done regularly to keep your pool clean.

There are several reasons why vacuuming is a good way to keep your pool clean. One of the most obvious is that it removes dirt and leaves from the pool. It also prevents insects and parasites from breeding by removing their habitats, such as branches, leaves, and other vegetation. 

Check out the WYBOT 2023 Premium Cordless Robotic Pool Cleaner with its easy-to-use push-button interface and convenient handle for easy transportation. Whether you have an in-ground or above-ground pool, it is the perfect choice for keeping your pool clean and inviting.

2. Scrub Your Pool Walls and Floor With a Brush

Pool Algae: Scrub Your Pool Walls

The brush will help to remove the pool algae from your pool surface. It also helps break up the algae’s cells to make it easier for the pool’s filter to remove them.

Make sure you’re using a brush that is exclusively designated for your pool and one that is appropriate for your type of pool.

3. Use Test Trips and Kits to Balance the Water

Pool Algae: Use Test Trips and Kits to Balance the Water

If the level of chemicals is too low, it can result in an overproduction of pool algae. Inversely, if the level of chemicals is too high, it can decrease pool algae production.

The best way to handle this issue is to ensure that your pool’s water has a correct balance of chemicals by using test strips and kits. You’ll need to know how your pool started out when setting up a chemical balance, so you know what you’re working with and where you need to get it.

4. Shock Your Swimming Pool

Shocking your pool is another way to prevent algae from growing. A shock will kill any algae that may have grown on the walls or in cracks of your pool. It would be best if you also shocked your pool after using a suntan lotion, as this can contain sunscreen that could attract algae or other contaminants.

Pool Algae: Shock Your Swimming Pool

When shocking your pool, avoid using stabilized chlorine. You’ll wind up with an excessive amount of cyanuric acid, which inhibits sanitizer and may result in algae growth in your pool or other, more severe issues down the road.

Remember to shock your pool after the sun goes down or at night. The sun will exhaust most of the chlorine if you shock during the day, which will prevent it from having a chance to destroy the algae effectively. Also, while you are shocking your pool, place your cleaning equipment at the shallow end so that it will be disinfected as well.

5. Retest Your Pool’s Chemistry

If you want, you may use your standard testing procedures or send a water sample to your local pool shop for examination. You want to ensure that your water’s chemistry is balanced and that the chlorine level has returned to normal before allowing anybody back into the pool.

6. Make Sure Your Pool Filter Is Clean

Clean your filter thoroughly because the last thing you want is to fill your pool back with microscopic algae that could start another bloom. You can deep clean the filter by soaking it in muriatic acid for a few minutes or just buy a new one. 

Preventive Measures for Algae Growth

Preventing algae growth is a challenging process, but it doesn’t mean you have to give up. Here are some of the most common techniques for preventing algae from growing in your pool:

The first thing you have to do is to make sure you’re using the proper equipment. Use a brush and a vacuum system regularly on your pool’s surface to reduce algae growth. It is also essential that your filter has been thoroughly cleaned and not filled with debris or other bacteria, leading to a pool algae bloom.

When draining your pool, don’t create an introduction for new contaminants into the water at all times because this can result in a breeding ground for algae and other microbes that could contaminate the water.

Using specialized chemicals or algaecides is also advised to back up the regular sanitation and filtration procedures. Here are some chemicals you can use for proper filtration and prevention of algae growth.

Potassium Tetraborate

Potassium Tetraborate is a type of algaecide that can be used to kill algae. It also improves the sanitizer’s ability to kill bacteria, just like Calcium Hypochlorite.

It has physical and chemical properties that enable it to target specific types of algae and doesn’t kill other substances in your pool, such as stings or scales.


Chitin is a natural substance that pool owners use to fight off algae for years. It works by binding to the cell wall of the algae and prevents it from reproducing, which in turn will kill it. Chitin is often found in spas and water parks because of this ability.

Phosphate Remover

Phosphate Remover helps prevent algae growth in your pool. It works by preventing phosphates from attaching themselves to the side of the walls, which is where most algae prefer to grow.


Algaecides are chemicals that kill off or inhibit algal growth and help keep your water clean and clear. They’re made for specific types of algae not to affect other organisms such as bacteria or stings in your pool. 

Monochloramine Tetraborate (MCBT)     

This product contains chlorine, hypochlorite, and monochloramine tetraborate.

Chlorine Enhancers

Chlorine Enhancers are a type of liquid chlorine that has been modified to be more potent and more effective against pool algae.

A pool would use Chlorine enhancers when it needs more chlorine in the water but doesn’t want to add any more than what is required. Chlorine enhancers also fight off algae by promoting the production of chloramines.

Filter Cleaners

Filter cleaners are a type of algaecide that can be used to clean the filter and kill pool algae. They work by killing or inhibiting the algae from thriving. 

Muriatic Acid

Some pools have a specialized pH level, which results in it taking a lot longer for the chlorine to sanitize them. This can cause an overgrowth of algae, so adding muriatic acid to the said pool may help prevent this from happening. The increased acidity will kill or inhibit the algae from growing in your pool.

Remember the adage “An ounce of prevention is worth a pound of cure”? This works for your pool. Prevent your pool from becoming ill-algae, and you’ll never have to worry about costly repairs trying to turn it back. Maintaining your pool regularly will keep it in good condition and free of algae. It may be time-consuming, but it will be well worth it in the long run.

Frequently Asked Questions (FAQs)

How can I prevent algae from growing in my pool?

Preventing algae growth involves regular maintenance. Maintain proper sanitizer levels (chlorine or salt), balanced pH and alkalinity, and adequate water circulation. Regularly brush pool surfaces, clean filters, and vacuum debris to minimize nutrients that algae feed on.

What should I do if I notice algae in my pool?

If you notice algae, take immediate action. Brush the affected areas to break up algae colonies and improve chemical effectiveness. Shock the pool with a higher dose of chlorine or non-chlorine shock treatment, and run the pool pump continuously until the water clears.

What causes pool algae to thrive?

Algae thrive in warm, stagnant water with imbalanced chemistry. Sunlight, debris, and high pH levels can contribute. Poor circulation, inadequate sanitizer levels, and irregular maintenance also create favorable conditions for algae growth.

Are there natural methods to prevent and treat algae?

Yes, some natural methods can help prevent algae. Using enzyme-based products can break down organic matter, reducing algae’s food source. Additionally, maintaining appropriate phosphate levels and using natural clarifiers can aid in algae prevention.

How often should I clean my pool to prevent algae buildup?

Regular maintenance is key. Clean the pool at least once a week by skimming debris, brushing surfaces, and vacuuming. Test and balance water chemistry regularly to ensure sanitizer effectiveness and prevent nutrient buildup.

Here are some tips on how to keep your pool clean and healthy. Swim in a clean, safe pool with your family for a fun time!

Photo of author

About the author

Brian Anderson

The rather dry pool world out there is in need of some passion to make it shine. With the help of my son Ruben and his wife Maria our mission is to help you create the favorite spot of your house - your pool.

Related Articles...

Leave a Comment