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Phosphates In Your Pool Water? What to Do Now!

Phosphates In Your Pool Water? What to Do Now!

As a pool owner, you’ve probably heard that phosphates can be harmful to your pool. And it’s understandable if the phosphates levels in your swimming pool making you nervous. Phosphates are everywhere. They can get to your swimming pool in many ways, and it’s close to impossible to keep it free of them. If the idea of having them in your swimming pool isn’t giving you peace of mind, then don’t worry.

This article will shed light on everything you need to know about phosphates and how they affect swimming pools. You will learn what phosphates are, how phosphates affect the swimming pool, the best ways to maintain phosphate levels in your swimming pool, and the dangers of high phosphorous levels.

What Are Phosphates?

Phosphates are chemical compounds containing phosphorous. They are primarily naturally occurring elements, but they can also be made in the lab. They are used mainly in fertilizers as nutrients for plants, beauty products, and pool chemicals. They are found also found in rotting and decomposing leaves and water supply.

Phosphates are everywhere. That means it’s close to impossible to remove them from your swimming pool 100%. According to multiple studies, their levels must reach at least 1000 ppb (parts per billion) to impact algae growth.

Are Phosphates a Problem?

Phosphates are the number one food source for algae; the more phosphates in the water, the more food for the nasty algae. However, keeping the pool water chemistry balanced and ideal sanitization is enough to ensure the algae doesn’t survive in your swimming pool.

Adding algaecide and shocking your pool occasionally even decreases the chances of the algae becoming a problem. That means, even if you have high phosphate levels in your pool, you shouldn’t worry that much. Besides, the phosphate compounds are safe – they can maintain their oxidation.

Phosphates won’t cause any skin or eye irritation, as some claim, and it doesn’t consume chlorine as many pool owners assume.

What causes high phosphate levels in swimming pools?

Even though it’s doubtful for the phosphates to reach dangerous levels, they can. Understanding how they are entering your swimming pool can help eliminate them. Phosphates get in your pool primarily in three main ways:

1. Chemical phosphates

The phosphates come from various sources, but mainly they are introduced by the chemicals you put into your swimming pool.

Many of these chemical phosphates can be found at atmospheric levels and as phosphoric acid and tripolyphosphate, often used to keep algae under control or sometimes even for sanitizing purposes.

The latter is significant because it might result in high phosphate concentrations that cause problems with a swimming pool’s ecosystem.

You see, once phosphate molecules get dissolved into water, then there’s no way back – phosphoric acid will remain active until it gets neutralized somehow (with baking soda). So if you’re using any acids like this regularly, you might be contributing to phosphates in your pool.

2. Organic Matter

Organic phosphates are also a problem. It can come from various sources, but most likely, it will be introduced into the pool through human presence.

Well, phosphates are often found in various cosmetics or even shampoos. If someone uses any of these products while taking a swim, the phosphates might get into your pool.

And with phosphates often used as nutrients in fertilizers, when the running water enters your swimming pool, it introduces them in the pool water.

What’s more, the plants around your swimming pool can also contribute to phosphates when they enter your swimming pool. During decomposition, they release phosphoric gas that mixes with water and dissolves.

One more source could be an animal waste, but it is doubtful for phosphates to come from this source unless you have some wild animals that frequent your swimming pool.

On top of all these, Phosphorous-containing waste products from various organisms might end up inside your swimming pool if their populations aren’t controlled enough or even when there are floods nearby.

Finally, organic matter comes with algae’s presence as well. Algae feed on phosphates, and they can grow in a pool that is loaded with phosphates. If you have an overgrowth of algae, the phosphates that these tiny creatures create will end up in your pool water, thus contributing to high phosphate levels.

3. Water Source

Sometimes phosphates can come directly from the water you use to fill your pool. This is especially common when you get water from rivers or lakes.

While phosphates themselves won’t dissolve in the water, they will be attached to other particles, and after that, even phosphates can enter your pool with it.

You see, phosphates are often found in various rocks, which means that phosphates are likely to be in it whenever there’s a source of water.

Even when using city water to fill or topping off a swimming pool is an option, this supply often contains high amounts of phosphates added to protect the plumbing from corrosion.

How to Prevent Phosphates from Entering Your Poo?

Even though it’s not easy for the phosphates to reach the dangerous level, 1000 ppb, you might want to keep their flow minimal. So, what can you do to prevent phosphates from entering your swimming?

1. Use pool water filters

Using pool water filters is a great way to maintain the phosphates levels in your swimming pool. These help trap phosphates, which means less of it gets into the waters, and you can then keep them clean more efficiently.

It’s also worth noting that some models include an option that allows you to collect phosphates in one place so you can remove them later.

It’s great because it makes phosphates removal easy, and you don’t have to worry about your pool safety in the meantime.

I recommend you check for one that uses an anti-phosphate filter or even phosphate inhibitors.

2. Clean Your Swimming Pool Regularly

Use a pool brush to dislodge any debris that might be sticking pool floor and walls. Use a vacuum to remove them from the swimming pool entirely.

Cleaning out your skimmer can also help prevent phosphates from entering your water by removing debris that collects there during the week while you are not using it. Cleaning around this area is essential because phosphates get stuck in these areas, which turns into phosphates in the water.

3. Cover Your Pool When not in use

You can even cover your swimming pool when not in use. A pool cover can help prevent organic debris such as leaves (a known source of phosphates) from getting into the water. It will also reduce evaporation, and it’s great for protecting your chemicals.

An excellent place to use a pool cover is in the winter when no one is swimming or even using it at all. A suitable cover for a swimming pool is solar blankets because they reflect UV rays, preventing algae growth and phosphates from entering your water.

Solar covers are generally very affordable to purchase but can last up to three times longer than other pool covers. However, less expensive options such as plastic sheeting and mesh pool covers can also reduce the amount of leaves entering your pool.

4. Landscape the area around your swimming pool area.

One of the easiest phosphates you can prevent from entering your pool is landscaping around the pool area.

This helps cut down on phosphates in your waters primarily because it reduces phosphates runoff into them, which means fewer phosphates for water to absorb and no contaminants that need cleaning out later on.

Landscaped areas are also better at absorbing sunlight, which results in lesser algae formation since algae feed off phosphates as well – so making sure there’s none where it thrives will be beneficial!

While landscaping the pool area;

  • Reduce fertilizer use near pools. Avoid fertilizing your lawn or landscape within 50 feet of the swimming pool.
  • Make sure driveways are clear of oil/gas drippings, avoid letting rainwater into them -ensure there is proper drainage after rainfall.
  • If leaves are entering your pool via high winds, you can also build a small fence around the area to prevent this.

5. Keep the Pool Chemistry Balanced Always

By keeping your water chemistry balanced, you can ensure that it never grows to be fed by the phosphates in your pool.

Check chlorine levels regularly. The FC level should always be above 0.60 ppm. Keep pH at a safe range between 7.6 and 7.8 and alkalinity between 80-150ppm and not higher than 200 ppm.

If all of these numbers are well within their ideal ranges, you shouldn’t be concerned with phosphates since the algae won’t be able to grow in your pool.

6. Add Algaecide Regularly.

If your area water has many phosphates that the hose filter can’t handle, consider adding algaecide to your swimming pool regularly.

That will ensure any algae spores that survive the pool sanitizer don’t bloom to become a nuisance later. If the spores were to grow and find food (phosphates) ready, you could end up having a huge mess to deal with.

Is Phosphate Remover Necessary for Pools?

Phosphates will still get to your swimming pool, one way or the other. Yes, the phosphates are food for the algae and an issue to the natural water bodies, not to forget some drinking water sources.

However, the level of phosphates in your swimming pool isn’t that high to cause the issues experienced by phosphate toxicity.

And since you won’t be draining your swimming pool often, it means your phosphate-laden pool water won’t be reaching your municipal systems regularly.

Another thing, if you’re a conscientious pool owner that keeps the pool chemistry balanced at all times, you’re already making an effort to ensure algae doesn’t grow in your swimming pool.

Besides this, if you add algaecide to your pool from time to time, you’re making the pool water hostile to the algae decreasing the likelihood of the algae spores developing.

I don’t see the need to spend more money on another chemical to stop feeding something you have worked so hard to prevent from growing in your swimming pool.

What’s more, here are some of the reasons that might convince not to use a phosphate remover:

Some Phosphate Removers Are Toxic

Some popular phosphate removers feature an active ingredient, Lanthanum, a soft metal that works on phosphates. It’s classified as a rare earth element and almost 3-times abundant than lead.

Scientific journal Ecotoxicology and Environmental Safety did a study in 2016 with the title Aquatic Ecotoxicity of Lanthanum. They aimed the research at reviewing and attempting to derive water and sediment quality criteria. On their findings, they came up with some interesting findings of the rare metal, Lanthanum.

Lanthanum is usually classified as ‘moderately toxic,’ and this study does seem to support this. And even though phosphates are algae food sources indeed, they aren’t in any way toxic. However, the study did find out that the element you add to your swimming pool when you add the phosphate remover, Lanthanum, is toxic to freshwater crustaceans.

The research even suggests that the availability of these elements is highly influenced by pH and other cations present in the environment. Organisms can accumulate it and, in the end, interfere with their cellular functions.

However, more studies are needed to determine the full extent of the Lanthanum toxic levels to organisms with humans included. But the small information available doesn’t support it’s the safest way to remove the phosphates.

Phosphate Removers Affects Sequestrant Effectiveness

Assuming you use well water high in copper and iron. Somehow, these two metals find their way into the swimming pool. If left unchecked, the copper ions could turn your pool cloudy and green, while iron can give the pool surfaces a nasty rusty brown color.

So, you rush to the pool store and get a metal sequestrant to help get rid of them. The sequestrant is supposed to bind with the metals to prevent oxidation, thus preventing their effects on your swimming pool.

And since the most influential metal sequestrant products are phosphate-based and you add them in the same water that you added a phosphate remover, the effectiveness of the sequestrant will reduce.

The phosphate remover will lower the phosphate levels in the sequestrant, which are supposed to bond with the metal ions and prevent oxidation. That means the sequestrant will have little to no success in preventing the effect, meaning you wasted your valuable money on two fronts.

Pro Tip: If you’re trying to deal with an algae problem by removing the phosphate levels in your swimming pool, it might not be as effective as you might want it to be. The algae presence is more likely to be caused by another underlying issue that the phosphate remover won’t solve.

Can a Phosphate Remover Affect a Salt Chlorinator?

It’s not once or twice I’ve come across pool owners claiming that the phosphate levels in their swimming pool are the cause of their chlorinator’s inability to produce enough amounts of chlorine.

But it can be the other way round. There could be high phosphates in your swimming pool because your pool chlorinator isn’t producing enough chlorine to kill the organisms and contaminants producing them.

So until we see hard evidence, we’re going to stick with our advice that a phosphate remover is unnecessary, even in a saltwater pool.

But since there is no scientific evidence that supports this theory, I will stick with my advice that you don’t need a phosphate remover unless the phosphate levels are nearly 1000 ppb, something only achievable only in an extended period.

If your saltwater pool has high levels of phosphates and your chlorinator is not producing enough chlorine, you might want to start by checking if it’s built to handle your pool size.

If it is ideal for your pool size, you can try supplementing it with regular chlorine from time to time, depending on where you live and the area’s environmental conditions.

Also, consider stocking the swimming pool regularly to ensure you get rid of the phosphate-producing organisms and keep algae at bay. When it rains, try shocking with double the standard dose.

You want to rule out the possible causes of low chlorine levels and the status of your pool chlorinator before rushing and feeding your pool with the possibly toxic phosphate remover.

Related Questions

Can you swim in a pool with high phosphates?

Phosphates are neither toxic nor harmful. That means you don’t have to worry about the high phosphate levels unless they are above 1000 ppb. If you maintain the ideal pool chemistry levels, use the sanitizer, algae and shock your pool occasionally, your swimming pool will be 100% safe.

Do phosphates deplete chlorine levels in your pool

No! Phosphates won’t deplete chlorine levels in your swimming pool. They two are not even related directly. The phosphates maintain their oxidation states all by themselves, meaning they don’t react with the chlorine ions.

About the author

Sharif Miah

Hi! I'm Sharif, the founder of Globo Pool® and I have been working in the pool & hot tub industry for the last few years. I love to share my experiences with people & hope you are enjoying my information and lessons!


  • We recently had our pool
    Opened and the company added 64oz of Omega Super Mineral Wlimjbator. When we closed our pool in the fall, our phosphates were 570. Our phosphates after opening are now 6100. Free Chlorine and total chlorine are both 6.59. PH is a little high at 7.8( we are adding acid). Cyanuric acod is 31 ( we will be adding). Salt is 2903. Water is crystal clear. Is it safe to swim with these phosphate levels?

    • Swimming in this state won’t have serious effects on you but you may experience some skin and eye irritation. The problem, however, is with the state of your swimming pool. Phosphate is the swimming pool algae’s food source. So, if the phosphate levels in your pool are high, you’re essentially giving algae a buffet. You might be surprised to find your pool filled with slimy algae in just a few days. Another thing, the phosphates will consume your free chlorine, making it ineffective against bacteria and other contaminants. You have to lower those levels if you don’t want to end up with a green pool or spend a lot of money to keep chlorine levels balanced.

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