How to Get Rid of Algae in Your Pool Quickly

At some point, every pool owner has to deal with algae in the pool. But what should you do if you have a problem with pool algae?

Green and yellow algae in the pool can be easily removed with a pool brush, a flocculant, and a little algaecide. However, the black algae have to be removed from the pool laboriously with pool shock and a filter run time of 36 hours.

This article is all about algae infestation in the pool. I will explain how algae are formed, which species exist and how to remove the algae from the water.

Remove pool algae quickly

There are several species of algae, and the most popular of these are green algae.

Different measures and pool cleaners are necessary for each type of algae to get the pool clean again.

But basically, the necessary pool equipment against algae is limited to the following utensils – you can find all recommended products via the links:

  • Chlorine granulate against targeted algae control on the ground.
  • Liquid chlorine can be used for shock chlorination.
  • Algaecides inhibit the growth of algae.
  • The classic pool brush for scrubbing.
  • Protective equipment consists of protective goggles and a mask.
  • Means for optimizing the pH value (pH plus and pH minus)

If you want to get rid of the algae in the pool, you can’t avoid the listed agents.

Of course, other tools and equipment such as a water tester are necessary. Still, as I said, these are the main tools to eliminate pool algae permanently.

As the article progresses, I’ll list the rest of the pool equipment and explain how they are used to eliminate algae in the swimming pool.

#1 Remove algae in the pool with a pool brush

A gentle way to remove algae from the pool is to use a classic pool brush.

With the brush, the algae deposits are removed from the surface in your pool – Alternatively, you can also use an electric pool robot – This only works if there are green algae or mustard algae in your pool.

To do this, scrub the pool over a large area and filter the pool water for 6 to 8 hours until it is clean again.

Then measure the pH value and, if necessary, optimize it with a pH lifter or with the pH reducer to 7.2 to 7.6 – the ideal pH value is 7.4.

In most cases, scrubbing and filtering are sufficient to remove the algae – without the additional use of chlorine.

To improve the filter performance, I may recommend using a flocculant. In the blog article, I explain how the flocculant is used.

Alternatively, you can use a hydraulic pool vacuum to vacuum the floor.

Tip: You can find a detailed article on cleaning a green pool on the blog.

But what should be done if there are no yellow or green algae in the pool but black algae clouding the water?

A standard pool brush is not enough if you have black algae in your swimming pool.

For black algae (also known as blue algae), you need a steel brush to break through the hard protective armor of the algae.

Furthermore, shock chlorination is necessary for black algae – otherwise, you cannot get this extremely stubborn type of algae out of the tank.

The black algae are mainly found in concrete pools, nestling in joints. A steel brush can be used without hesitation to eliminate the black algae.

To be safe, I would like to mention that you shouldn’t use a steel brush in a liner or GRP pool, although black algae are less common in a liner, GRP, or stainless steel pool.

Should the blue-green algae ever end up in the pool, you will quickly find help in the following text.

#2 The shock chlorination against algae in the pool water

Shock chlorination (shock chlorination) is an efficient method to disinfect a pool.

If you have a major algae problem in the pool, shock chlorination can work wonders in most cases.

A pool shock is not always necessary with green, brown, or yellow algae in your pool. But a pool shock is still needed with the dreaded black algae.

You can perform a pool shock in different ways:

  • The use of chlorine granules that are specifically sprinkled on the pool floor.
  • Or the use of a highly concentrated liquid chlorine.

My first method (sprinkling with chlorine granulate) is suitable for large areas of algae infestation on the pool floor. The type of algae or its color is irrelevant here.

In addition, with this method, you do not necessarily have to scrub your pool beforehand.

Scattering your pool with chlorine granulate may make scrubbing with the pool brush a little easier.

  1. First, switch off the pool pump and put on your protective equipment (respiratory protection, rubber gloves, and protective goggles).
  2. Now move forward with the pool shock. To do this, sprinkle the pool with the chlorine granulate generously and do not aim at individual spots in the pool.
  3. Let the chlorine act for 24 hours to create a chlorine cushion. 
  4. Also, pour some algaecides into your pool (do not overdo it and follow the manufacturer’s instructions).
  5. After the 24 hours have elapsed, the pool is scrubbed with the brush.
  6. Start the pump continuously until the water clears again (24 hours should be enough).
  7. In the meantime, measure the pH value and, if necessary, improve it with pH plus or pH minus to 7.2 to 7.6.

Important: Wait for a windless moment before you start distributing the chlorine granules in the pool.

It is not uncommon for beginners to experience large amounts of chlorine in their eyes when performing a pool shock. You should always wear a certain amount of protective equipment using pool chemicals.

Do not use the pool until the chlorine level drops below 1.5 ppm. Nobody should swim in the pool beforehand.

Tip: Many advisors recommend a pH value of 7.0 and 7.4. A pH value below 7.2 is already on the verge of acidic pool water and threatens to tip over. The pH limit at 7.2 – 7.6 has proven to be the best.

#3 Remove algae from the pool wall

But what if algae are not only found on the bottom, but the algae have also attacked the pool walls?

Suppose the algae are infested over a large area in the swimming pool. In that case, targeted sprinkling with chlorine granulate is not possible.

For this purpose, I recommend the second method – shock chlorination in the pool with liquid chlorine and the use of a pool brush.

  1. If you have black algae in the water, scrub the entire pool with the steel brush beforehand to improve the effectiveness of the chlorine.
  2. Pour the liquid chlorine into the flow of the return nozzles. Alternatively, you can dissolve the chlorine granulate beforehand in the bucket and pour it into the pool.
  3. Pour an algaecide into the pool to stop the algae from growing again.
  4. Scrub the entire swimming pool in between to improve the effectiveness of the disinfectant.
  5. Let the pump run for 24-36 hours with the addition of a flocculant to remove the dead algae from the water.
  6. Test the pH value in the pool water and, if necessary, check the pH value to 7.2 – 7.6.

I will explain below in the text how the chemical is dosed correctly in your pool or whirlpool.

The liquid chlorine is dosed differently depending on the manufacturer. But you can use the following rule of thumb as a guide:

  • With a chlorine content of 80 g/l, 10 liters of liquid chlorine per 25 m³ of water are used.
  • With a chlorine content of 150 g/l, 5 liters of liquid chlorine per 25 m³ of water are sufficient.

In the article, I have linked you to a good and relatively cheap liquid chlorine.

Remind: You should only swim your pool after the water levels ​​are correct:

  • The pH level should be 7.2 – 7.6.
  • The alkalinity is measured between 80 and 120 ppm.
  • Calcium hardness in pool water should have a level of 200 to 400 ppm.

Fight the algae in the pool with a flocculant

Suppose you notice that the pool water is becoming cloudy. In that case, I recommend using a flocculant that can combat algae in your pool.

With the pool flocculant, the algae and other fine particles floating freely in the water are bound to form large flakes and filtered out more efficiently by the filter system.

How the flocculant is used in the pool, I explain here:

  1. For a better result, adjust the pH value to 6.5 – 7.2 first.
  2. Then, according to the manufacturer, the flocculant is preferably used in a skimmer. Alternatively, the following rule of thumb can be observed: 200 ml flocculant per 10 cubic meters of pool water.
  3. Let the filter system circulate the water for 2 – 4 hours.
  4. Turn off the pump and let the pool sit overnight.
  5. The flakes can be vacuumed with a pool vacuum or a pool robot the next day.
  6. Then let the filter system run through as usual until the pool becomes clear.
  7. It is advisable to pour an algaecide into the pool.

Use the flocculant every 14 days to prevent clouding of your pool water and to kill algae in your pool.

If a large pool area is infested with algae, then the flocculant alone is not enough. In this case, I recommend my complete cleaning plan against cloudy pool water.

Use an algaecide against algae in the pool

The algaecide alone is not enough to completely remove pool algae from your pool.

It is more of a killing agent that should also be used as a preventative against algae.

Algaecides are available in different concentrations and, depending on the manufacturer, they foam strongly, slightly foam or non-foam.

If you use an algaecide without the steps I described, your green pool likely just turned into a brown pool.

The pool water becomes dirty because the algaecide kills the algae, and dead algae are usually brown.

To remove the dead algae from your pool, you should let the filter system run for a few hours – read the instructions described above.

Tip: I recommend adding approximately 125 g of chlorine per 25 m³ of pool water in combination with the algaecide to strengthen the effect of the pool algaecide.

Then the filter system has to go through until the water is clear again – you don’t have to switch off the filter while adding the algaecide.

Further down the text, you will find more helpful information about green algae in your swimming pool.

Prevent and combat algae in the swimming pool

With my tips, you should now be able to clean a pool that has become cloudy from algae.

As an extra, I want to give you tips on preventing algae in the pool. After all, prevention is better than scrubbing the pool afterward.

  • Increase filter running times: If algae form in the tank, it is mostly because the running times of the filter system are too short. Check the runtimes and increase them if necessary.
  • Scrubbing the pool regularly: Pick up the pool brush and use it to scrub the pool at regular intervals. It is much easier to scrub the pool with light pressure than to later loosen the hard-nested algae with the pool brush. Pool robots are wonderfully suited to have the pool cleaned automatically daily.
  • Pool Floater: With a floater, you can continuously produce free chlorine in the pool and thus inhibit algae growth. You had to place a chlorine tablet in the floater.
  • Copper sulfate: Copper sulfate is an inexpensive algaecide based on heavy metals. Therefore, the information on the dosage must be followed so that there are no side effects.
  • Ionization: Electrolytic processes are ideal if you want to avoid algicides. With such a system, the pool owner will be spared algae in the pool for many years.
  • Silver-containing products: Unfortunately, few silver-containing products are available for the pool maintenance, but they are very effective against algae in the pool water. And the best thing is that these products are not harmful to people or equipment.

Always make sure to measure the water quality with a water tester.

Suppose the pool is contaminated with algae despite the good water quality. In that case, you will quickly find help against algae in this article.

Alternatively, you can watch the following video.

Do you have any further questions about algae in the pool?

Then use the internal search function or contact me at @contactswimfool on Facebook, YouTube, or Twitter – I’ll be happy to help.

With that in mind, have fun cleaning your pool.

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind swimfool.com, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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