What Causes High Phosphates In Pool Water? How To Lower It

What Causes High Phosphates In Pool Water? How To Lower It

Let me guess…

You may have heard that phosphates can eat up the chlorine in your pool and cause algae blooms. Now, you are experiencing frequent algae blooms.

If that is the case, you are taking the right steps. However, there is more to that, which you will learn if you stick till the end. But before we dive deeper, let’s address the question, “What causes high phosphate levels in swimming pools?

There are several factors that can cause high phosphate levels in your pool. 

  • One of them is the detergents you use. If you use detergent to wash your swimsuits, you need to rinse them very well because the detergent contains phosphates. If not rinsed well, the phosphate will enter your pool through the swimsuit.
  • Phosphate is found in skincare and hair products. When you swim in your pool, these products get deposited in your pool, which introduces the phosphates into them.
  • Runoff water can deposit phosphates into inground pools. This is true because runoff water can carry fertilizers, debris, and decomposed organic matters that have phosphates in them already.
  • Is your pool always open? You are likely to have high phosphate levels if you allow leaves and debris to fall into the pool. When these organic compounds decompose, they can introduce phosphates into the pool.
  • Phosphate can also get into your pool through pool chemicals. So, you need to be careful with the amount of chemicals you use in your pool.
  • Last but not least, is your pool water supplier. You should endeavor to test the water you are using in your pool. The phosphate content might be high already. So, test the water before filling your pool with it.

Now that you have known the potential causes of high phosphate levels in a pool, the next step is to know the true effects of phosphates in your pool. Also, you need to know if there are ways you can lower it without impacting your health negatively. 

As a professional who provides services to pool owners, I have come to realize that many pool owners believe that algae blooms are a result of high phosphate levels. 

So, do phosphates cause algae growth?

Yes, phosphate can cause the rapid growth of algae in a pool because it is the major source of food for them. 

Algae heavily feed on phosphates, so if you have high phosphate levels in your pool, it will attract algae into the pool. Once the algae are attracted, they can multiply very fast with the presence of that phosphate.

So, phosphates do cause algae growth in pools. Even in the presence of chlorine sanitizer, phosphate can cause algae blooms.

Do phosphates eat up chlorine?

So far, there are no research studies that provide such information about pool chlorine and phosphate. From our high school chemistry, we only know that phosphorus can react with chlorine gas to form trichlorides. 

Since you only use liquid chlorine and chlorine tablets in your pool, it is almost impossible for the two chemicals to react. So, it’s reasonable to say that phosphates do not directly eat up the chlorine in pools.

However, phosphate can indirectly affect pool chlorine. Since phosphate can cause algae growth in a pool, it means that it can also cause high chlorine demand in the pool.

If there is incessant algae growth in your pool, the amount of chlorine required to disinfect the pool will increase, thus causing the chlorine to deplete faster.

So, if you are wondering if high phosphates can cause chlorine lock, the answer is “no”. It can only cause high chlorine demand through algae growth.

Does chlorine lower phosphates?

As we discussed earlier, when organic matter decomposes, it can release phosphates into the pool water. Organic matter is known to be one of the major causes of high phosphate levels in a pool.

When algae die, the dead particles can decompose and release phosphate into the water. But if you limit algae growth in the pool, the amount of phosphate released decreases.

This is the only way chlorine can be used to lower phosphate in a pool. It does not directly lower phosphate levels in the pool. But it can lower it by preventing algae growth in the pool.

As we discussed above, chlorine does not react with phosphates in pool water. So, it cannot lower the phosphate levels.

What removes phosphates from pool water?

If you are contemplating how you can lower the phosphate levels in your pool, then you have to consider using phosphate removers.

You can get them from the pool stores or suppliers. But you need to understand that most of the chemicals are toxic and can affect your health.

So, you don’t necessarily need to use them since phosphates are not that toxic. However, if you deem it necessary to use it, you should meet a professional first to guide you on how to go about it. 

Having excess phosphate remover in your pool is dangerous, so you have to avoid it by all means.

Moreover, phosphate removers can react with some metallic components of your pool. Some metal industries use phosphate to protect the metals from oxidation. 

Metals like copper and iron can undergo oxidation. To prevent that, some manufacturers use phosphate in their production. 

So, when you use phosphate removers in the pool, it can affect those components, which would subsequently lead to the oxidation of the metals.

It simply means that, apart from health issues, phosphate removers have the potential to cause further problems in the pool.

How do I control phosphates in my pool?

The best way to control phosphate in your pool is to prevent it. By all means, avoid the use of phosphate removers. They are not good for your health.

We have listed the most common causes of high phosphate levels in pools. The best action to take is to look for ways you can prevent phosphate from entering your pool.

Some of the measures include:

  • Ensure that swimmers shower before entering the pool.
  • Cover your pool to prevent debris and leaves from entering.
  • Avoid pool chemicals that contain phosphate. Check the labels to know the ingredients used.
  • Rinse your swimsuits properly after washing with detergents. Preferably, don’t wash with detergents.
  • Prevent runoff water from entering the pool.
  • Test the water before filling your pool. Etc.

Do I need to remove phosphates from my pool?

Phosphate is not that toxic to health, so there shouldn’t be much concern about it. The only concern is that it can cause rapid algae growth.

So, if the level of phosphate in the pool is not too high, you don’t need to bother yourself about it. But, if it becomes excessively high, you need to consider reducing it.

At this point, adding a small amount of phosphate remover may be needed. However, make sure you don’t add too many chemicals because they are very toxic.

Can you put too much phosphate remover in the pool?

Adding excess phosphate remover is not advisable. That’s why you need to work with a professional to help you determine the appropriate amount of chemicals to add to your pool.

If you don’t have an expert to work with, you can consider using the natural method. The natural method can be time-consuming and require more work.

How do you remove phosphates from water naturally?

A lot of people recommend using algae to remove phosphate from water. But that method is not recommended for pool water. You can use algae in the water that will undergo further treatments. 

But, if you must use algae in your pool, you need to shock the pool properly after treatment. You don’t need algae in any form in your pool. So, shock treatment is necessary after using the algae.

The best natural alternative is activated carbon. The negative side of using activated carbon is that it can also affect other pool chemicals, like the chlorine level in the pool.

Since activated carbon absorbs chlorine as well, you need a high dose of chlorine sanitizer during the treatment to help maintain the chlorine level.

During this period, you need to stop using the pool because of the high chlorine level.

Nevertheless, after removing the activated carbon, you need to test the water and make any necessary adjustments to the pool chemicals.

Does shock remove phosphates?

No, shock treatment can only be used to kill algae in a pool, but it does not remove the phosphate in the pool. 

Nonetheless, shock is important in the control of phosphate in the pool. The organic matter that decomposes to release phosphate in the pool can be removed through shock treatment.

Does pool clarifier remove phosphates?

No, pool clarifiers are only used to remove tiny particles that your pool filter can not remove. The clarifiers achieve that by coagulating the particles together to form clogs.

They don’t react with chemicals like phosphate, so they cannot be used to remove them.

However, a clarifier can be used to prevent the release of phosphate into the pool by removing tiny organic matters. 

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