How to Get Rid of Algae in Pool: Everything You Need to Know

How To Get Rid Of Algae In Pool

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Maintaining your pool is often relatively straightforward once you get used to the job. However, the challenges often arise when you have to deal with things like algae, which is quite a common occurrence if you do not take precautions to prevent it.

While it is still safe to swim in a pool with algae, it can be a breeding ground for bacteria, and it also makes the pool unsightly.

The good news is that it is easy is to get rid of, and here we show you how and provide tips for preventing its growth.

What is Algae?

Algae is a microscopic marine organism that is often present in most water bodies in small quantities. However, for it to be visible to the human eye, it must bloom first. Blooming is where the algae cells will grow, feed, and subdivide, and hence leading to more algae on the pool, which is when it becomes a problem.

There are different ways for algae to enter your pool, from being blown in by the wind to being brought in swimsuits and contaminated pool equipment. The three common types of algae that will typically appear in pools are the green, yellow and black algae.

  • Green Algae: Green algae is what comes to mind when you think of pool algae as it is the most common type. This algae type will float freely in the pool, which results in the water becoming murky and greenish. However, this algae type is also the easiest to remove from your swimming pool.
  • Yellow Algae: Yellow or mustard algae is often mistaken for sand in the pool given its color, and so many pool owners will not intervene early enough. This type grows in the shady areas of the swimming pool, such as the bottom and along the walls. Because it can survive in pool toys, pool scrub brush, and even the pool filter, it requires extra attention to prevent re-infection.  
  • Black Algae: Black algae are the hardest to get rid of, and if you encounter it, you should be ready to put in a lot of work and time to remove it. The algae create some deep roots on the pool floor and sides, and if you do not remove all its roots, it is almost certain that it will come back.

Note: While the three types above are the most common pool algae types, there are still many other types that you can encounter, such as the pink, red and brown algae.

Why is Algae Bad for Your Pool?

Why is Algae Bad for Your Pool

  • Clogs Filters: Because algae tend to clump up together and reproduce, it can end up blocking the filters. Clogged filters lead to poor circulation and hence worsening the problem by providing the perfect breeding environment for algae.
  • Traps Bacteria and Germs: Overall, algae are not harmful to you or your pets, but it can trap bacteria and germs, which can have adverse health effects. Algae provide food for bacteria, some of which can lead to skin irritations and other issues like ear infections.
  • Makes Steps and Surfaces Slippery: Algae makes the steps and other surfaces slippery, and hence increasing the likelihood of accident falls in the pool.
  • Erodes Surfaces: With algae in your pool, it can alter the pH level of the water, which then leads to the buildup of minerals like calcium and scaling. Over time, the scaling and calcium deposit will erode pool surfaces like fiberglass and concrete
  • Makes Pool Unsightly: The presence of the green, yellow, or black algae bloom over the water in your pool creates an unsightly look. Besides the algae being ugly, it will also cause staining and discoloration of the swimming pool, which makes it even more unappealing.

Symptoms of Algae in Your Pool

While the symptoms of algae in your pool will depend on the specific type you have, here are the most common and general ones.

1. Water Changing Color

The most obvious symptom that your pool is infested with algae is the water surface changing colors. In an algae-free swimming pool, the water should be clear, and you should be able to see the bottom. Hence, if you notice that the water is green, yellow, or black, this is a sign of algae.

2. Changes in Water pH

As a pool owner, the chances are that you check the water temperature and pH often to make sure the pool will be as comfortable as possible. When you find the pH level higher than usual, this can be a symptom that you have algae as it causes a rise in the pH. But, because there are still many other things that can lead to pH rise, you cannot rely on this symptom alone.

3. Pump and Filter not Working Well

One of the most common effects of algae on your pool is that it can clog the filters, which in turn can affect the functioning of the pool pumps. Hence, when you notice that the pool water is not getting filtered adequately or effectively enough, and the pumps seem to have a lag, you need to check whether you have algae.

4. Skin Irritating After a Swim             

When you have algae in your pool water, you will often end up with an irritating skin after your swim. Algae and the germs and bacteria that it breeds are known to cause skin itching and irritation.

How to Get Rid of Algae in Pool

Get Rid of Algae in Pool


1. Shock your Pool

Shocking your pool is one of the most effective ways of getting rid of contaminants that ordinary chemical seem unable to remove. The process entails super-chlorinating water to kill algae and anything else that does not belong in there, such as chloramines.

Here are the steps to follow:

Step 1: Wear Protective Gear

Because you will be dealing with potent chemicals that can harm your skin and eyes and also bleach or damage your clothes, the first step should always be to wear protective clothing. Make sure you have gloves and safety glasses and clothes that you will not mind ruining.

Step 2: Mix the Chemicals

Next, you should mix the chemicals, and what you need to do and the ratios for mixing will depend on the specific pool chlorine shock you have. But the good news is that most will come with clear mixing instructions.

Some types, like lithium hypochlorite, do not require any mixing as you pour them straight into the pool while others, such as the granular shock, have to be dissolved in about 5 gallons of water. The type of algae you have matters here because black algae will require a more potent mixture than others like green and yellow algae.

Read More: The Best Pool Shock

Step 3: Shock Your Pool

Adding it to the swimming pool is what shocks the water and kills the algae. Here you will also need to follow the manufacturer instructions. Some will only require you to disperse the mixture evenly on the pool, while others specify you pour the mixture close to the jets to ensure efficient circulation.

Step 4: Leave the Mixture to Work

Next, you now need to allow the pool shock mixture to do its work. The manufacturer will provide instructions on how long you need to leave the pool unused after the treatment, but for most products, overnight is often enough.

Step 5: Check Pool Chemistry

Once the recommended time has elapsed, you will need to check the chemistry of the pool’s water before you can allow anyone to use it. Make sure that the pH is standard, which for most pool waters is between 7.2 and 7.6.

Read More: The Best pH Meter

Step 6: Filter the Water

The last step is to filter the water by running your filtration system. Shocking kills algae and other contaminants, but it does not remove them from the water. Hence, by running the filtration, you can discard them.

Note: Always shock the pool at night or dusk because if you do it during the day, the sun eats up most of the chlorine before it gets the chance to kill the algae. Also, as you shock the pool, keep the tools and equipment you use to clean the pool in the shallow end so that they are sanitized.

2. Floc your Pool

Floc or flocculant is a type of chemical that will take algae and other small particles from the pool water and settle them at the bottom of the pool for you to vacuum them out.

While this method works well enough for removing most algae types and can do it quite fast when done correctly, it can be tedious.

Here is how to flock your pool.

Step 1: Shut-Off Pump

You do not want water flowing through the filter or in and out of the pool, and so the pump should be shut off. You want the water to recirculate, which is to move around the pool as this will help mix in the floc chemicals you will add in the step that follows. Most pool filters will have a recirculate or recycle function, which is very useful when flocking.

Step 2: Add Flocculant

You should now add the flocculant to the pool water, and here you will need to make sure you add the right dosage according to the size of your pool.

For example, if you are doing maintenance, you will need around just 5 ml of liquid flocculant per 10m³ of water. But, when dealing with algae, you will typically need between 100 ml and  200 ml of the liquid flocculant for the 10m³ pool.

Note: Flocculant manufacturers will often provide clear directions on the dosage you need to use for different pool sizes, and so you should have an easy time figuring out how much to use.

Step 3: Leave the Water to Circulate.

With the flocculant in the pool water, you should leave the water to circulate for a few hours or according to the manufacturer’s instructions. About 2 hours is often enough for most products and most pool sizes.

Once the product is mixed into the water adequately, you need to leave it to do the job overnight. The chemical will bond to the algae and cause it to settle at the bottom, and so the next day, you should find a particle cloud at the bottom of the pool.

Step 4: Vacuum the Particle Cloud

With a vacuum cleaner, you can now remove the particle cloud at the bottom of the pool. Make sure you do not turn on the pump when vacuuming, as you will not want the particle cloud going through the filters.

Also, as you vacuum, you can use a garden hose to add more water to the pool to replace what you are removing. And when things become too cloudy as you vacuum, you can leave the job for a few hours to allow for resettling of the particles.

Note: This method tends to clog filter cartridges, and so you should avoid it if your pool uses this cartridge type, and you are not ready to replace it afterwards.

3. Use a Pool Algaecide

Algaecide is a specialized chemical for killing algae, and so it will also be an effective way of removing algae from your pool. In most instances, these products are just a combination of acid and chlorine, and so for maximum effectiveness, you might need to add lots of them.

Using algaecide can prevent the need for taking drastic and more costly measures like flocking and shocking. There is algaecide for specific algae types and multipurpose ones that can work for any algae type.

This method is quite simple as it only entails adding the algaecide to the pool water, mixing it well, and then brushing your pool as you usually do when cleaning the swimming pool.

Tips to Prevent Algae from Coming Back

Tips to Prevent Algae from Coming Back


1. Keep Circulation System in Good Working Condition: Ensuring your circulation system is in good working condition is one of the most effective ways of keeping algae at bay. And this is because it ensures the waste is always clean and sanitized so that there is no conducive environment for algae growth.

2. Maintain Water Balance: Besides keeping your water clean and sanitized, you also need to maintain water balance to prevent the growth of algae. This means you will need to keep the alkalinity, pH, cyanuric acid, and calcium levels at optimal levels.

3. Add Algaecide Regularly. Algaecide not only works as a method for removing algae from your pool but can also help prevent it from forming in the first place. Hence, it would help if you made it a habit of adding it when treating the pool water.

Read More: The Best Algae Eaters

4. Maintain a Brushing Routine: Routine brushing of steps, floor, and walls on your pool can also help keep algae at bay. These are the most common areas where algae will grow, and so by simply brushing them often, you can brush off any algae before it takes roots. But, make sure you use a soft brush to prevent scratches and other damages.

5. Eliminate Phosphates: Algae are living organisms that will need nourishment to survive, and so if you deny them food, they will die out before they even start growing. Phosphates are a common food source for algae, and it can come from sweat and also being blown in by the wind. There are different chemicals you can add to your pool regularly to eliminate phosphates.

6. Clean Swimwear Before Wearing: Contrary to what many people might assume, swimwear is quite a common way of introducing algae to your pool, and this is more is if you wear it when swimming in the ocean. Hence, before using the swimwear in your swimming pool, you need to make sure you clean and sanitize it to kill any algae.

7. Keep a Watchful Eye: You should also keep a watchful eye to ensure you detect any algae growth before it blooms and becomes a big problem. Even if the pool is not used a lot, you should make sure you check it as often as possible to prevent algae growth.


Algae is one of the most annoying things that you might need to deal with as a pool owner because, besides giving the pool an unsightly look, it can also damage things like filters.

The good news is that most algae types are relatively easy to get rid of, and you will often only need a few simple pool cleaning tools and chemicals, and of course, some time to spare.

From shocking the pool to adding algaecide, there are different ways to deal with the problem. The best thing you can do is prevent the issue to ensure you never have to deal with it by taking good care of your pool.