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Phosphates In Your Swimming Pool

It’s funny that we never hear customers complain about phosphates being in their pool until their pool is green. Did you know that phosphates are always in your swimming pool, even when there are no algal blooms? That’s because it doesn’t cross your mind when your pool is nice and blue. After reading through various articles and customers’ questions on removing phosphates, I’ve come to one conclusion, there’s a lot of misconstrued and misconceptions regarding phosphates in your swimming pool. What exactly are phosphates? Where do they come from and how do phosphates get into your swimming pool? What is the threshold for phosphates before it becomes harmful to the swimmer?

Let’s explore phosphates a little more.

What Are Phosphates?

Phosphates are nutrients that help increase plant growth. Naturally, you can find phosphorus material all around. That is why it is common for phosphates to be in your swimming pool. But how exactly do phosphates enter your pool? There have been many debates suggesting how phosphates enter your swimming pool. Some argue that excess rainwater or fertilizer can affect your phosphate levels. Which is true, sort of.

How Do Phosphates Enter Your Swimming Pool?

Phosphates might enter your pool one of several ways, but rainwater is not one of them. Rainwater itself isn’t phosphorous. In fact, it’s impossible as phosphates do not atomize in the atmosphere. However, once the rainwater runs off into the soil, then it becomes phosphorous. Usually, swimmers bring the majority of the phosphates into the pool with them. Contaminants like makeup, lotions, shampoos, dirt, leaves, and other pool chemicals like scale and stain products account for the majority of the phosphates in your pool.

When and How You Remove Phosphates From Your Pool

Whenever you have an imbalanced pool, one of the first things you should do is test your water. Before you can remedy the issue, you first need to determine what the issue is, right? So what happens when the store clerk tells you your water has a high amount of phosphates? Naturally, the first thing pool owners do is go out and purchase a phosphate remover and add it into their pool.

If you’ve already experienced this, you already know that this won’t solve your green pool. Now, you have a green pool AND white sediment at the bottom of your pool. The first thing pool owners should focus on is removing the algae. In this particular case, once the pH and alkalinity levels were correct, the water was clear. To be honest, there probably wasn’t a need to purchase the phosphate remover. In most cases, you won’t have a need for phosphate remover.

In fact, there is no scientific evidence that even proves that phosphates actually increase algal growth rates when phosphate levels are below 1000 parts per billion (ppb). McGrayel Water Technologies completed a study and it was determined that algal growth rates are unaffected at each phosphate level. They also determined that phosphates are not likely to be a problem until after levels are above 1000 ppb.

Before adding phosphate remover into your pool, make sure you actually need it. We do not recommend adding unnecessary chemicals into your pool. Remove phosphates from your pool when levels exceed 1000 ppb. Once your phosphate levels exceed 1000 ppb, I would consider purchasing a phosphate remover. Keep in mind though, phosphate remover will not rid your green pool.

Reduce the high cost of removing phosphates by being proactive. Keep in mind, phosphate remover is preventative, not a remedy. Test and treat phosphates annually. There isn’t a need to worry about them constantly. Instead, focus more on keeping your pool properly balances.

author avatar
Charlie Ramirez
Writer at InyoPools.com, brings a wealth of knowledge and expertise in pool care and equipment, helping pool owners make informed decisions for over a decade.

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107 responses to “Phosphates In Your Swimming Pool”

  1. Don Avatar

    I was told that phosphates are steroids for allergy…so you really don’t want any at all in your pool

    1. Jennifer Avatar

      Yes they very much so are!

    2. G.W. Avatar

      For someone with a known specific allergy, it certainly can be. Common seasonal allergies are unlikely to be affected. Besides, the level of 1000 ppb translates to one part per million, which is detectable, but rarely a problem; consider this in light of the fact that a BAC of 0.01% concerts to 100ppm.
      Hope that was helpful!

      1. Faith Avatar

        Not only does it exasterbate allergies but pollen in itself IS a phosphate. So there’s that.

  2. Mark Avatar

    Same problem as others…2000 – got rid of algae – added remover – shocked it twice – can’t get a free chlorine reading – add clarifier – water is pretty blue but cloudy – starting to think draining the pool is cheaper…….

  3. Lynn Avatar

    My phosphate level was 1000 and I was told to add PhosFight. My water was crystal clear before and all chems were balanced. After adding the phosfight, it’s cloudy. Instructions say to run filter for 24-48 hours then backwash. Is it normal for this stuff to make the pool cloudy?

    1. Curt Avatar

      Yes, it will make the pool cloudy

    2.  Avatar

      How did you get rid of the cloudiness? I am having the same problem.

  4. Curt Avatar

    I just bought phosphate remover. We are gonna try the remover first. I went through all the forums and made a bunch of phone calls. Got alot of different answers but the most common answer was to treat the phosphate issue. Then introduce chlorine back into the pool. Please keep us informed.

    1. G.W. Avatar

      I hope everything went well in the summer of 2018. As a professional in CA, where there is a huge pool industry base, I can validate the information in the article, and say that in the future, balancing the water ( Chlorine, pH, and Cyanurate level), which the article recommends, should always be the first step in correcting any water quality issues, esp. with problems like algae or staining. Balancing the water then physically brushing the algae will almost always correct the issue in the short-term. The exception to this is if there is high TDS or a non-soluble suspended in the water.
      Once the water is balanced and the algae no longer visible, that is the proper point to test phosphates and use a removal product.
      Hope that helps, and wishing you good gortune and fun summers!

  5. Laurie Avatar

    Phosphates down to 2400 after second treatment. Water still is crystal clear. I am getting conflicting opinions on whether it is necessary to treat these phosphates. My biggest concern is I can’t keep a chlorine reading in my water. One pool supply store is recommending we drain significant amount of water and at noon and the other is saying don’t worry about it just do what we would normally would do with chlorine and pH as long as the water still clear. It has been almost a week since we have been able to treat it with chlorine with the 85° weather at this point I need to worry about algae. Thougjts? where do I go from here?

    1. Faith Avatar

      Shock the crap out of it. That’s what we had to do in order to get our to register. I initially did 3 bags of shock and algaecide to open the pool (whoops you don’t use both within 24 hours) and it turned blue but super cloudy…. Shocked it again with another 3 bags, nothing. Added cya stabalizer to the min required levels….. Added SIX yes SIX bags of shock, and we finally get our chlorine up. Then still to my surprise very very cloudy but blue. Everything was balanced, took water to the pool store and phosphates were at 3600… So now we’re working on that…. And now the pH went down and all went up 🤷 I don’t even know anymore but I know we have chlorine in the pool now.

  6. Curt Avatar

    We are having exactly the same problem as Laurie. Took a water test today to pool place and said our phosphate was extremely high. We have shocked our pool 5 nights in a row and every morning there test say no free chlorine using test strips and by having water checked. Going to buy phosphate remover today. Looking for good product. Any help be appreciated.

    1. Faith Avatar

      Swimables phosphate remove x is what I just purchased. Out levels were at 3600 for a 13,000 gallon pool. If one bottle of phosfree spring and fall only clears 300ppb for 25,000 gallons that means about 600ppb for our pool…. That’s ALOT of phosfree or buy at $20 a bottle. I got a liter of swimables remover x for $32 and it’s concentrated to uses less product to remove more ppb. Hope it does the trick. I’m not going to have my water tested until 48 hours… It’s stressing me out

  7. Laurie Avatar

    We get results tomorrow. prIor to the first phosfree treatment we had used flock and clarifier As I mentioned pool water is crystal clear our biggest problem is being able to keep chlorine in the water That is why we had the water tested and they found it was high and phosphates They indicated that the phosphates eating the chlorine that is why we could not keep chlorine in the pool

    1. Mary Ethridge Avatar

      Try looking up chlorine demand and taking corrective action as outlined

  8. Laurie Avatar

    The product did not require that I bypass the filter. it stated to pour in the skimmer and run for 48 hours and then backwash. we are on our second treatment. We don’t know what to do next

    1. Matthew Simmons Avatar

      What were the results after your second treatment? have you used a clarifier or floc in combination with the phosphate remover?

  9. Laurie Avatar

    My water is crystal clear. Phosphate at 2450 after one treatment of phosfree. Was at 2550. Only dropped 100 after first treatment. Chlorine is now gone. Our second treatment is in process. Should we see our pressure on a sand filter increase? We did not our first treatment and the pool supply store was shocked. We have a sand filter. This is our second year with it.

    1. Matthew Simmons Avatar

      After the treatment, did you backwash and rinse your filter? Also, some phosphate agents require that you bypass the filter media, by setting the multiport valve to recirculate. This is because those phosphate agents clog the filter. Did your instructions have this step?

      1. Laurie Avatar

        Yes we backwashed after the firat treatment The pressure never changed with the first treatmen. We back washed after the first treatment and have a sample tested again It only went down by 100.
        My questions are: 1- SHould my sand filter build pressure? 2 – is it noRmal to have the water be crystal clear with high levels of phosphates?

        1. Matthew Simmons Avatar

          As stated in my previous response, if you used a product that required you to bypass the filter media but you did not do so it could cause clumping and clogging.

          Yes, you can have clear water with high phosphates.

          1. Kelly Avatar

            Hi, I had phosphate level at 1300 so my pool company told me to get commercial phosphate remover. It worked. I just poured in pool like he told me to and I feel like I have to backwash a lot cause my flow light keeps coming on???

          2. Matthew Simmons Avatar

            The flow light on what piece of equipment, a heater, salt system, VS motor control? That is important to know, to be able to determine how to fix it.

  10. Steve Avatar

    Is there a chemical compound substitute that I can use instead of the expensive PhosFree products..Example, I use soda ash to raise the PH,,can buy in bulk very cheap.
    Thanks

    1. Matthew Simmons Avatar

      I have not found a home remedy phosphate remover yet. Still on the look hour for one.

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