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Cyanuric Acid: the complete guide for your pool

(Almost) Everything You Need to Know About Cyanuric Acid

If you are going to keep your swimming pool crystal-clear and healthy enough for swimming throughout the entire summer season – or all year round, even – you’re going to need the right mix of chemicals added at just the right time to get the job done.

Chlorine alone isn’t enough to handle the heavy lifting of keeping your water clear and healthy, either.

You’ll need chemicals to sanitize your water, to balance out the pH levels that can get crazy depending on the different chemicals you are adding, something to combat ammonia and algae – and even something to cut down on the cloudiness that can be caused by a whole host of different issues.

But even the most powerful pool chemicals sometimes can’t handle everything on their own and need a bit of a universal assistant to sort of pump them up. That’s where cyanuric acid comes into play.

Sometimes called a chlorine stabilizer, cyanuric acid plays a major role in cleaning and maintaining your swimming pool and by the time you’re done with the inside information we highlight below, you’ll know (just about) everything there is to know about cyanuric acid and how to use it effectively.

What Exactly is Cyanuric Acid, Anyway?

Before you start dumping powerful chemicals into your swimming pool it’s critical that you know exactly what they are and exactly what they do, and that’s what we are going to zero in on a right now with cyanuric acid.

Cyanuric acid is technically a chemical compound classified as a triazine which is basically a fancy way of saying that it has three individual nitrogen atoms and three individual carbon atoms. This makes cyanuric acid very chemically strong but also helps it to offer a bit of a foundational boost to other chemicals that can draw from these atoms – like chlorine.

In fact, a lot of products free combine cyanuric acid and chlorine as well as other chemical stabilizers and shock treatments so that you don’t have to worry about mixing these chemical components together all on your own.

How Does Cyanuric Acid Work?

The way that cyanuric acid works is really simple and straightforward but it also has to do with the way that sunlight impacts traditional chlorine.

You see, your pool currently has three different types of chlorine in it right now (even if you are only adding one source of chlorine yourself).

Free chlorine is the amount of chlorinated sanitizer available to actually clean your pool at any one particular point in time. This is the chlorine that you introduce directly into your pool or the chlorine created by saltwater chlorinators, depending on the system that you are using.

Combined chlorine, the other hand, is the amount of sanitizer that has already been used up in the process of killing off bacteria and scrubbing everything else from your pool as well. It’s no longer as chemically active but it still exists in the pool and needs to be dealt with.

Total chlorine, at the end of the day, is (unsurprisingly) the amount of free chlorine and combined chlorine that is sitting in your pool water.

After introducing chlorine into your swimming pool it immediately transforms through a chemical process into sodium hypochlorite ions. When rays from the sun (ultraviolet rays) hit those ions they begin to split apart, dramatically reducing the amount of free chlorine that exists in your pool faster than you ever would have thought possible.

Researchers have proven that within 17 minutes of exposure to ultraviolet light more than 50% of your free chlorine is gone completely. Yes, that means that in less time it takes to watch your favorite TV show in the summer half of the chlorine you’ve added to your pool to clean it has already been destroyed by the sun.

Thankfully though, with the addition of cyanuric acid you don’t have to worry about that evaporation having that same kind of impact on free chlorine alone.

The free chlorine that you add to your pool is going to immediately bond with the cyanuric acid that has been introduced into the water, preventing the sodium hypochlorite ions from being eradicated and evaporated by UV rays.

This means that you can expect your free chlorine to destroy bacteria and scrub your pool for anywhere between three and five times longer than it would have been able to on its own – all while letting you use a lot less chlorine at the same time (saving a mountain of money and keeping your pool healthy and clean).

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Should I Be Using Cyanuric Acid in My Pool?


As we just highlighted above, chlorine on its own is going to be devastated inside of 17 minutes – and it isn’t going to take all that much longer of UV light exposure for the rest of the free chlorine that you have added to be destroyed, too.

30 minutes or so isn’t anywhere near long enough for a couple of scoops of chlorine to clean your pool and kill off harmful bacteria.

With the introduction of cyanuric acid to stabilize that chlorine, however, you dramatically extend the life of the chlorine and the utility of it. This means less chlorine makes its way into your pool but more chlorine handles the heavy lifting you’d expect it to, resulting in crystal-clear water and healthy swimming pools to enjoy without you having to spend a mountain of money on dump trucks full of chlorine just to keep your pool open.

Any Drawbacks to Using Cyanuric Acid?

It’s really important that you perfectly dial in the amount of cyanuric acid you are adding to your swimming pool, though or you could actually inadvertently handicap the impact of both chlorine and cyanuric acid at the same time.

Pool owners that add to much cyanuric acid to their swimming pool (or allow ambient cyanuric acid levels to get to hide) will effectively eliminate the effectiveness of chlorine entirely.

Chlorine won’t be able to do its job at all but will instead be choked out by the higher amounts of cyanuric acid, and that means that you’ll have wasted money adding chlorine to your pool, wasted money adding cyanuric acid to your pool when it wasn’t necessary and wasted a lot of time, energy, and effort while being left with a pool that is dirty and unhealthy to swim in.

This is why it is so critically important that you stay on top of your chemical levels. As soon one of these levels gets out of balance or out of whack it negatively impacts everything and it takes a whole lot more energy to right the ship than it does just to maintain perfect balance.

How to Consistently Hit Perfect Cyanuric Acid Levels in Your Pool

According to information released by the World Health Organization, you want your cyanuric acid levels to stay at around 50 ppm in your swimming pool.

You could go as high as 100 ppm, but that 50 ppm limit gives you a bit of a buffer zone assuming that children (and some adults) are going to swallow a bit of swimming pool water every now and again and you don’t want to negatively impact their health.

Higher concentrations of cyanuric acid that go above 50 ppm also start to push your pool chemically to a level where algae and bacteria growth can really take off if it doesn’t stay on top of consistently.

Algae, in particular, can be very difficult to get rid of after it establishes itself – and if you’ve started to notice your pool getting a little cloudy or a little murky the odds are pretty good that you need to adjust both your chlorine and cyanuric acid levels ASAP.

Tips for Lowering Cyanuric Acid Levels When Necessary

If cyanuric acid levels are starting to creep up higher and higher far too quickly for you to allow them to balance out naturally it’s not a bad idea to troubleshoot this issue yourself.

For starters, you’ll want to check to see if you are using stabilized chlorine when you thought you were using “raw” chlorine in conjunction with cyanuric acid. Stabilize chlorine already includes a bit of cyanuric acid on its own and you may be adding more than you expected because of this.

If cyanuric acid levels continue to rise it’s not a bad idea to drain at least a little bit of your pool and then refill it with fresh and untreated water. Some cyanuric acid is still going to reside inside of your filtration system and you may need to do a backwash if levels continue to remain high after a flush and refill, but for the most part, this is going to level things out pretty quickly for you.

At the end of the day, managing your swimming pool with the help of chlorine, stabilize chlorine, and cyanuric acid, in particular, becomes a whole lot easier when you understand how all these different chemical components work in tandem with one another.

The quick guide above hopefully has provided you with enough information to feel comfortable using cyanuric acid more effectively moving forward. It’s one of the most powerful chemicals around to help you maintain your swimming pool to perfection and you don’t want to miss out on the benefits it brings to the table.

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