How to Use Cyanuric Acid In Your Pool

Finding out that you need to adjust your Cyanuric Acid (CYA) acid levels can be overwhelming at first. Though it may sound like something to panic over, your pool’s high or low CYA reading isn’t a tragedy. It is a safety and health issue, but one you can fix.

In this article, we’ll walk you through all you need to know about what it is, what job it does in your pool, and how to adjust your CYA levels. You’ll have your family back in the pool before you know it.

What Is Cyanuric Acid?

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Cyanuric Acid (also known as chlorine stabilizer) is a chemical stabilizer, and it’s structure allows each molecule of it to attach to three chlorine molecules. It’s not a strong attachment, and the chlorine can break away, at least in theory. The type of structure it has is known as a triazine.

Triazine is taken from its chemical structure, which includes three nitrogen (N) atoms; those are where it can pair to the chlorine. While it is paired to chlorine the chlorine is not as effective, but there’s a reason it’s used in pools, we’ll get to that next.

While it is essentially a non-toxic chemical at less than 100 ppm, when there is too much or too little in your pool, it can cause problems. That is because cyanuric acid is a conditioner, and here’s why you use it in your pool.

Why Would You Want to Use it in Your Pool?

You don’t need to use CYA in indoor pools, but for outdoor pools, it’s essential. When the sun’s UV rays hit the water in your pool, they can break down the chlorine in the water. In fact, just a few hours of strong direct sunlight can destroy up to 90 percent of the free chlorine in your pool.

The chlorine plays an important role in sanitizing, so having it essentially burnt out of the water on sunny days is not good for your pool. In fact, without cyanuric acid, you’d have to use up to eight times the chlorine to keep your levels right.

There are different types of chlorine that you should know about:

  • Total Chlorine: All of the chlorine in the pool, including combined and free
  • Combined chlorine: Used chlorine, which has already killed bacteria or algae
  • Free chlorine: Ready and raring to go, this is freshly added to the water and actively sanitizing your pool

Cyanuric acid is a stabilizer or conditioner, and it bonds with the free chlorine in your water until it has bacteria or algae to kill. The problem is that too much CYA is almost worse than too little, though both are big problems if you have an outside pool.

You want enough CYA to keep your chlorine from succumbing to the sun’s rays. That helps keep your pool water clear, healthy, and sanitary. However, you don’t want too much. We’ll get more into the downsides below. But first, how it works.

How Does Cyanuric Acid Work?

CYA acts like a sun protectant to the chlorine in your pool. When the molecules of chlorine take shelter in the molecule of CYA, they aren’t damaged by the sun. Cyanuric acid stabilizes the amount of chlorine in your water, stopping it from leaching out.

Think of the CYA as a floating umbrella, the chlorine grabs a hold and floats along with the protective cover. While it’s protected, chlorine can’t do its job if it isn’t able to sanitize. However, it’s not stuck there, as the bond is weak, it can let go. So, when chlorine is needed, it releases.

Cyanuric acid conditions your water, allowing the chlorine levels to stay optimized. That means avoiding gross green algae, bacteria, or other noxious and unhealthy issues to develop. There are, however, some negative aspects of using CYA in your pool.

Downsides of Cyanuric Acid

CYA lowers the effectiveness of your chlorine, slowing down its ability to keep your pool sanitary. The effectiveness of chlorine is called the ORP (oxidation reduction potential), which is a measurement of how well the chlorine in your pool is working.

Because CYA, regardless of how much you use, lowers the ORP of your chlorine, it should be used at the lowest effective level. If you add too much CYA or allow it to build up over time, you’ll find your chlorine completely ineffective.

Chlorine has to be able to kill dangerous additions to your pool, to keep you and your family safe. However, it also has to be present (and not completely dissipated by the sun) in order to do that. Striking the right balance with your CYA level is, therefore, pretty important.

Ideal Cyanuric Acid Levels and How to Adjust Them

While the safe upper limit for cyanuric acid in your pool is 100 ppm, according to the World Health Organization (WHO), that’s more than you need to condition your water and protect your chlorine. The lowest concentration that WHO recommends is 50 ppm, however, keeping your chlorine active is super important, so I would recommend sticking around 40-50 ppm.

Raising CYA Levels

Raising your CYA level is easy. To do it, you simply test (use a pool water test kit), add some, and it raises the levels. Some sanitizers known as stabilized chlorine, such as dichlor and trichlor, come with CYA added. So be sure to check your chlorine to make sure you aren’t adding any accidentally.

To add the CYA, be sure to read the directions and wear acid-resistant gloves and eye protection. We suggest not adding it directly to your pool water or filter, it is an acid and can damage the filter. After mixing it with water (or not, depending on the brand) pour it into your skimmer.

Lowering CYA levels

This is tougher. If your readings are just a little high, there are cyanuric acid reducers that you can use. Be sure to follow all safety information and warnings for any product you buy. However, they may not be effective.

The only thing that lowers high CYA levels is dilution, which means partially draining and refilling your pool. That isn’t the answer you want to hear, but it’s the only genuine solution.

If your levels are really, really high, you may end up having to fully drain and refill your pool.

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Government Regulations and Limits for CYA Levels

The CDC (Centers for Disease Control and Prevention) recommends keeping your pool pH at 7.2–7.8, and free chlorine at a minimum of 2 ppm if you are using CYA also. They don’t have a recommended level of CYA, though, unless yours is a commercial pool and you have a fecal incident.

Your local and state government may also have guidance for CYA levels, you will need to check on your local public health department website for that up-to-date information.

The Bottom Line on CYA and Your Pool

Pool care means keeping your levels balanced, including pH, sanitizer, and CYA. Chlorine is vulnerable to the sun, and CYA can protect it, but the trade-off is lower efficacy of your chlorine.

Striking the right balance, starting around 50 ppm and never over 100 ppm, is essential.

If levels in your pool are too low, under 30 ppm, you’ll need to get a lot of chlorine to adjust. If they’re too high, you’re going to need to dilute them, by at least partially draining and refilling your pool.

Your family’s healthy use of your pool depends on your sanitizer, stabilizer, and pH working together to keep your water safe and clear.

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