The Shocking Truth About Phosphates in Your Pool Water

Over time, every pool owner will be confronted with the phosphate in the pool. Is phosphate harmful? Do you have to remove the phosphate from your pool water, and if it is, what is the best way to remove the phosphate?

The phosphate in the pool is not toxic and does not necessarily have to be removed from the water. An anti-phosphate agent is redundant as the chlorine already kills the algae, and the pool water remains clean despite the high phosphate level.

In this article, you will learn the truth about phosphates in your pool water and what to do if the phosphate level is too high.

What do the phosphates mean in your pool?

Phosphate is a naturally appearing element on earth that can be found everywhere – in water, grain, fruits or meat, and much more.

It is also widely used as a preservative for milk and cheese products.

It is wrongly assumed that phosphates are toxic, but this is not true.

Phosphates are essential for human life and play a crucial role in energy metabolism and bone remodeling.

But what happens if there is too much phosphate in your swimming pool, and how does it affect the water parameters?

The phosphate is a nutritional basis for all organisms, and if the level is too high, it can increase the algae growth in your pool – the pool water turns green.

Sellers often mention this fact to sell unsuspecting pool owners an expensive phosphate remover (algae destroyer).

After all, as a pool owner, you don’t want to have algae in your pool, do you?

But this is only half the truth.

In reality, you don’t have to worry about the phosphate in your pool, as long as the pool water has already been treated with chlorine and an algaecide.

What I mean by that and why you don’t need a phosphate remover, I’ll explain in the next chapter.

Do you have to remove the phosphate in the pool water?

There is a lot of false information about phosphate on the internet that terrifies pool owners and motivates them to buy a phosphate remover.

But is a phosphate remover really necessary for your swimming pool maintenance?

As already mentioned, you usually do not have to buy a product to remove the phosphate from the pool water.

Even if you use a phosphate remover (algae destroyer) in your pool, this is no guarantee that your pool will be clean again.

The much more efficient method for water treatment are disinfectants such as chlorine granules or liquid chlorine.

The chlorine kills the algae and prevents unwanted algae growth.

With the addition of chlorine, your pool is freed from algae growth and disinfected from any other bacteria and germs simultaneously.

So why should you even spend extra money on a phosphate remover?

In short: If the chlorine is dosed correctly and regularly used in your pool with a chlorine stabilizer, you don’t need an extra anti-phosphate agent.

After all, most algae are killed by chlorine, and the phosphate agent seems to be redundant.

For this reason, I advise you not to buy a phosphate remover and to trust the tried and tested pool cleaning methods.

But at this point, I have to mention that algae can grow in your pool despite chlorine.

This can have various causes and be related to the filter run time or the general pool cleaning.

That is why I always recommend using an algaecide in addition to the chlorine to inhibit renewed algae growth.

The combination of the different pool cleaners and the water treatment is crucial.

I won’t go into more details in this article. Otherwise, it would go beyond the scope of this article. You can also find all the important topics about pool maintenance in my blog – use the search function.

However, it can’t hurt to lower the phosphate in your pool.

You can find out how to do this without a phosphate remover in the following chapter.

How to lower the phosphate level in a pool?

A high phosphate level can trigger blue algae blooms (cyanobacteria) – also known as black algae.

Therefore it can make sense to keep the phosphate level low.

To remove the phosphate from your pool water, you should first know how the phosphate gets into your pool in the first place.

This happens in different ways, such as when filling freshwater – which contains phosphate – or when organic substances end up in your pool and are not sucked off.

I mentioned at the beginning of the article that all substances contain phosphate.

To name just a few:

  • Leaves and needles from nearby trees.
  • Water beetles and flying water insects.
  • Dead algae in your pool.

All of these contaminants – which end up in your swimming pool – release phosphate into the water.

Therefore, the best way to get the phosphate out of the water is in the first place not to let the phosphate arise.

Use regularly a pool net, let the filter system run longer, and vacuum the pool floor.

If the organic matter remains in your pool for a more extended time, the water tips over, and your pool becomes cloudy.

Therefore, as a responsible pool owner, ensure that your pool is cleaned properly.

What to do if the pool water turns green

Eutrophication is when the pool water tips over and becomes cloudy.

Organic materials – such as leaves or dead algae – sink to the pool floor and get decomposed by bacteria.

During the decomposition of the organic matter, the bacteria consume excessive oxygen and at the same time release phosphorus, which increases the growth of algae and continues the cycle.

An over-fertilization is the result.

A pool shock with liquid chlorine is sufficient in the early stage.

You need 5 – 10 liters of liquid chlorine per 25 m³ of water, depending on the concentration.

After using the chlorine, the filter system must run through for at least 24 hours until the water becomes clear again.

With this method, you don’t need a phosphate remover, but the best thing to do is not to let your pool water turn green.

Phosphate agents in pool water can be toxic

I have already explained why the phosphate agent in your pool is entirely superfluous and why chlorine is a better alternative.

The phosphate is only a problem in lakes, rivers, and drinking water – your private pool or hot tub is not included.

The phosphate in your pool is indeed an essential food source for algae, but it is not toxic, which I cannot say of the phosphate remover.

Studies have shown that phosphate remover agents are toxic and harm the environment.

The reason for this is the heavy metal lanthanum it contains.

“Lanthanum can be easily absorbed by various organisms and disrupt cell functions.”

Aquatic Ecotoxicity of Lanthanum. Source.

I do not want to elaborate that heavy metals are carcinogenic.

Further studies are necessary to investigate the effects of lanthanum on humans and the environment.

Still, this quote from the study is enough for me not to use a phosphate remover in my pool.

Phosphate removers inhibit the effects of phosphoric acids

Using a phosphate remover not only removes phosphates from your pool, pool chemicals that contain phosphoric acids are also negatively affected – this includes many metal removers.

Suppose you discover pool stains caused by a high metal and copper content in your pool.

The metal clouds the water in a slightly brownish hue, while the copper in the pool water can turn your pool green.

What do you do in this case?

You decide to use a metal remover and ignore that phosphorus is a major ingredient in such pool chemicals.

The phosphorus combines with metal and iron and enables these substances to be filtered.

When using a phosphate killer, the effectiveness of all pool chemicals based on phosphoric acid is lost.

You lower the phosphate in your pool but prevent removing the iron content in the water and so literally throw money out the window.

Phosphate in the saltwater pool

The phosphate level is much higher in saltwater than in freshwater.

Some advisors claim that too much phosphate in your pool hurts the functionality of the chlorinator.

But there are no well-founded studies on this, and the claim is far-fetched.

If the phosphate level in your saltwater pool is high, it is much more likely that the chlorinator is not adapted to the pool volume and does not produce enough free chlorine.

Do you regularly use a pool shock to kill all organisms that produce phosphate?

Maybe increasing the number of pool shocks – performed per month – will solve your problems?

Review all possible measures before using a toxic phosphate agent in the pool.

Conclusion on the phosphate remover in a swimming pool

Through scientific studies and reputable sources, I have tried to clarify that phosphates in your swimming pool do not pose any danger.

With the discovery, it could be proven that you don’t have to spend additional money on purchasing a phosphate destroyer.

As a result, you save extra costs in pool maintenance and protect the environment if you don’t use an anti-phosphate.

I also explained that chlorine and algaecide in your pool are the better alternatives for pool maintenance.

With this in mind, I wish you a refreshing bathing season.

Do you have any further questions about phosphate in your pool?

Contact me at @contactswimfool on Twitter, Facebook, or Pinterest with your question – I’ll be happy to help.

Have fun learning more about pool maintenance in my blog!

Photo of author
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.

Keep Reading