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.



38 thoughts on “Phosphates In Your Swimming Pool

  1. Very helpful article! All my pool water samples in the summer were balanced except for slight problems with pH being too high, which we would treat with muriatic acid or pH Down. The phos always hovered right below the 500 which was noted as the “high normal “standard. I always worried about it but no more!! Knowing that 1000 is the limit helps a new pool owner! Looking forward to late spring 2018!!!!

    Thank you!

  2. Great information!! This site has given me a lot of knowledge about owning a pool. Many problems have been solved just reading the info posted in the email messages with the links to the articles. Keep up the great work!!!

  3. I’m fighting the phosphate battle right now. This is helpful. Had my water tested for phosphates. Came back really high. This is the first time EVER I’ve had this problem. The only thing I can attribute it to is that a high wind storm partially took off our [water bag] cover in the spring. Lots of yuck that was on top the cover mad its way into the pool water.

  4. I had my water tested and it was over a 1000.My water was a light green.I just added the remover today.I noticed some stuff on the bottom few hours later.Just wondering what i am to do after.All other levels are normal.I need the green gone

  5. Great article. I appreciate what you do with this site. Very informative. My pool turned a cloudy green over the span of 3-4 days. I’ve cleaned my filter cartridges and took my water into our local pool store to have it tested. The chlorine and pH levels are in line and actually a little high. However the phosphates are at 1000. So try suggested adding calcium to lower the phosphate levels.

    Sounds like this won’t necessarily clear up the pool so I’m not sure what’s happening to the pool. The only recent event I can think of is we recently turned on a pump for a waterfall in the pool and noticed the water in the pool pump was very green. Could that have circulated algae into the pool which then started feasting on all the phosphates?

    1. It doesn’t matter how many phosphates are in a pool, if chlorine is present in a sufficient enough number algae cannot live. Take a look at our how to clean a green pool article and video. I’m not sure where the algae came from, but if there is cloudiness, then your chlorine is working. Cloudiness after an algae bloom is a sign the algae is dying. Add shock and algaecide, to expedite the process. Keep your chlorine levels elevated, until the green is gone. Add clarifier to clear the cloudiness after the green is gone.

  6. Hi
    I live in Phoenix with current temps around 110.I also have many trees around my pool that shed debris into my pool. My phosphates are reading at 500ppm. Also my Chlorine is reading high right now. I purchased POSfree per the recommendation of the pool supply store. When I was reading the label it states.

    Important- Do no test Phosphates if the Chlorine is high. My question is, should I go ahead with using the Phosphate remover?

    Thank you

  7. Hello
    I’m having a phosphate problem for the first time this year. My phosphates were tested to be approx. 4600 ppb. After treating with commercial grade Phosfree and the highest strength phosphate reducer it is still testing at 4000 to 5000 ppb. Is there anything left that I can try besides emptying the pool and refilling?
    Thanks in advance for you help

    1. I would go with another treatment of the phosphate remover. Maybe try a different band.

      When draining the pool, I wouldn’t drain the pool completely, just like a third or a half.

    2. Biodex phosphate remover plus, it’s expensive but the best chemical I’ve come across. Dropped ppb by 2000 overnight

  8. We have given up and drained the pool to start over. What will we do with many buckets of phosphates that we will have to scoop out of the bottom?

  9. I ve had my pool running since May 19th 24/7. First it was the usual alkalilne ,ph, shock. The it was metal remiver, followed by iron remover, tons of schock, and liquid shock , then finally phosphate remover, Not once but twice . My pool is cloudy cannot see the lunar net it hittom at all . Phosfate reading 4699. What can be done ?

  10. 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.

  11. 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. 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. 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. 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.

  12. 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

  13. 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

  14. 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.

  15. 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?

  16. 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.

  17. 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?

  18. 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…….

  19. Got mine down to a count of 100, down from almost 4000 count. Used phosphate remover took 5 bottles. Restocked the pool. Gonna wait two days then have retest done.

  20. They say my Phosphate level 1000, my pool is clear not green could this be a bad test or should i use phosphate remover. Also isn’t PH plus and Aklalinty Increaser baking soda, if i raise one of them will it take care of both problems.

    1. Just because your phosphates are at 1000 it does not mean your pool is going to start turning green. If your pool is clear, then I wouldn’t worry too much about it. As long as you keep the chlorine levels in range, you will be fine.

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