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Cyanuric Acid: Friend Or Foe?


What Is Swimming Pool Stabilizer? 

If you have been working with pools and spas for any length of time, there is a good chance you have heard the word stabilizer, conditioner, or pool sunscreen used before. But what is water stabilizer? Do I really want a conditioner in my pool? And honestly, what is pool sunscreen!? All of these words like stabilizer, conditioner, and sunscreen are all words used to describe something called cyanuric acid. In this article, we will discuss what cyanuric acid is, how it works, its positives and negatives, and dosage recommendations. 



The simplest explanation for cyanuric acid is that it delays the effects of UV light on your chlorine. Believe it or not chlorine is highly prone to degradation when exposed to UV light. In fact, after one hour of exposure to UV rays, chlorine can degrade by as much as 50%! In an industry like the pool industry, where our pools live and die by sunny days, it is scary to know that those sunny days we are hoping and praying for are the very thing that is going to degrade our much-needed disinfectant! If only there was some way to stop this UV degradation from happening! Enter: Cyanuric Acid. 


How Does Swimming Pool Stabilizer Work?

Without going into too much of a scientific tirade, Cyanuric Acid is added to the water to create a protective "shell" of sorts around your chlorine. This shell (as we'll call it from here on out) helps slow down that UV from degrading the chlorine quickly. The science shows that using cyanuric acid in the water can slow UV-related chlorine degradation by 3-4 times! Those are good stats! In fact, Cyanuric Acid is wildly popular. It is popular primarily because many believe that it is beneficial for two reasons: 

  1. Cyanuric Acid Will Lower Your Chlorine Loss
  2. Using Cynuric Acid Will Save You Money


What Are The Drawbacks of Swimming Pool Stabilizer?

At this point, Cyanuric Acid seems to be a miracle product! After all, we all love spending less on chemicals, right!? But there are a few underlying issues with Cyanuric Acid that many of your chemical suppliers may not tell you about. These issues may very lead you to say no to adding Cyanuric Acid to your pool this summer. 

1. Cyanuric Acid Never Leaves The Pool

That's right! once it is in there, Cyanuric Acid never leaves the pool. Some see this as a benefit: once you add it, it never leaves. But the build up of Cyanuric Acid in the water has been known to cause some major issues in the water. The only proven way to remove Cyanuric Acid from the water is through draining and refilling the pool with fresh water. 

2. Cyanuric Acid "Traps" Your Chlorine

Once your Cyanuric Acid levels rise about roughly 25 ppm, it begins to hinder the effectiveness of your chlorine in the water. In fact, if Cyanuric Acid levels are high enough, it can render your chlorine useless. This means that high Cyanuric Acid levels can cause algae and harmful pathogens to survive unhindered in your pool. If you are using Cyanuric Acid in your pool, it is crucial to keep the levels low for this very reason. 

3. Cyanuric Acid Creates Major Headaches When Someone Poops In Your Pool

Cyanuric Acid presence in the pool during an Accidental Fecal Release (AFR) requires that you take stronger, more time consuming steps to inactivate potential pathogen contamination. In some cases, you will need to partially drain and refill your pool if your Cyanuric Acid levels are too high. To see exactly how you will need to go about dealing with fecal contamination while using Cyanuric Acid, refer to our article What Do I Do If Someone Has Pooped In My Pool? 

4. Cyanuric Acid Has A Close Relationship With Cyanide. 

 If given the right conditions in your pool, Cyanuric Acid can convert itself into Cyanide. Admittedly, this is a very rare occurrence, but it is still important to know all the facts when choosing to use certain chemicals. 


Does Trichlor Contain Cyanuric Acid?

The simple answer is, yes, the 3" tabs of Trichlor that are so popular in our industry to indeed contain Cyanuric Acid. When using Trichlor, it is crucial that you monitor and control the level of Cyanuric Acid in your water. 


How Much Swimming Pool Stabilizer Should I Use?

Pool Training Academy suggests you use as little to no Cyanuric Acid as possible in your pool. We hold this stance because we firmly believe that unhindered disinfectant in the water is crucial to keeping you and your guests as safe and healthy as possible. 

If you do decide to add Cyanuric Acid to your water to stabilize your chlorine loss, we recommend you keep the levels below 25 ppm. Indoor facilities, we suggest you don't use any Cyanuric Acid at all, due to the fact that your pools don't encounter any UV contact in the first place. If you are using 3" tablets of Trichlor in your indoor pool, we recommend you consider a different disinfection system such as a Calcium Hypochlorite Feed System.


How Do I Learn More About My Swimming Pool and Spa?

Making sure you know the benefits and drawbacks to Cyanuric Acid is only one of the many challenges pool and spa operators face on a day to day basis. Making sure you know what to do in any given situation is crucial for you as an operator. Thankfully Pool Training Academy offers Certified Pool Operator® Classes year-round and close to you. We offer CPO® classes from the Denver Metro Area to San Antonio, Texas, Los Angeles, CA to Nashville, TN. Please click here to sign up for the class that will ensure you are the best pool and spa operator you can be. 

2 Responses

Chris L.

Chris L.

February 20, 2024

In response to Jake Cole:
If intending to use an ioniser (and they are good contrary to what a lot of pool shops will tell you) – do ‘not’ use ‘any’ stabilzer products – e.g. cyanuric acid.
It is highly recommended to ‘only’ use un-stabilised chlorine with ionisers to prevent issues.
Several options now combine low salt chlorinators with ionisers so a regular level of un-stabilised chlorine is present without having to constantly manually add liquid chlorine etc.
You then just need to keep a check on pH levels, as the chlorine will up the pH and become ineffective if not kept at correct pH.
So an acid feeder may also be of benefit if you are a very low maintenance set up and don’t want to manually add every few days.
Hope this helps.

Jake Cole

Jake Cole

January 15, 2024

I currently do not use any stabilizer in my pool because I don’t like the idea of adding yet another poison to the water where I swim. Instead, I chlorinate the water periodically, say every two days, just enough to bring up the chlorine levels to 2-3 ppm and then keep it covered with the solar blanket until I go in to take a swim. I then keep the cover on most of the time until someone goes into the pool again. By doing that, I prevent most of the chlorine burnoff in sunlight. After the chlorine level goes down to zero or close to it, I do that again. I also shock the pool every two weeks or so as needed. This is a time-consuming process and I plan to try a mineral ionizer to try to minimize the chlorine necessary, even more. Although the instructions on the ionizer indicate that a little bit of chlorine is still required, .5ppm, I will try to minimize that too. I will be interested to see what effect the ionizer has. Idealy, I can get away with using less chlorine and maybe just a wee bit of stabilizer. I would be interested in knowing your or anybody else’s opinion of this proposed course of action.

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