Cyanuric Acid: What It Is, How It Works, and How to Keep Your Levels Perfect

It’s no secret that achieving the perfect chemical balance—and staying there—can be a struggle for any pool owner. It’s possible that the most challenging aspect of owning a pool isn’t closing it for the winter, dealing with overheating equipment, or possibly even needing to repair cracks in its walls. What can be even more frustrating is not knowing the problem in the first place, such as when you’re faced with a disgusting, murky pool, or algae that just won’t budge.

One common chemical that can help keep your pool to stay sanitized, but often gets overlooked? It’s cyanuric acid, and if you’re a new pool owner, chances are you’ve never heard of it. But although cyanuric acid never quite takes the spotlight, the entire chemical production of your pool—including the elimination of harmful bacteria—would be ruined without it. I’ll explain what cyanuric acid is, why chlorine depends on it, the downside of the chemical, and how to add cyanuric acid to your pool or dilute it to achieve the perfect levels—as well as how to keep it maintained for the long haul.

What is Cyanuric Acid?

When it comes to pool chemistry, cyanuric acid isn’t exactly the star of the show. But however minor a character it may play, it is absolutely essential to the proper sanitation of your pool. That’s because it allows the real sanitation star of your pool, chlorine, to actually work. Think of it this way: chlorine is the C.E.O., and cyanuric acid is the executive assistant. Without cyanuric acid to do the scheduling, chlorine won’t show up to work.

So what exactly is cyanuric acid? Well, we might have to get a little technical here, but don’t worry if you’re not in the mood to return to your high school chemistry class (I wouldn’t blame you, by the way). You don’t have to understand the nitty gritty details about cyanuric acid’s chemical makeup to ensure that it actually works in your pool. Essentially, cyanuric acid is a type of chemical compound called a triazine. This term refers to the fact that it contains three nitrogen and three carbon atoms. Okay, chemistry class over.

What do you need to know as a pool owner? Well, know that it’s also called CYA, pool conditioner, or pool stabilizer. You can also get it mixed in with chlorine in the form of chlorine tablets or sticks, called trichlor, and in chlorine shock, called dichlor. When chlorine is already combined with cyanuric acid, it’s usually labeled as stabilized chlorine. This saves you the time and effort of adding cyanuric acid to your sanitizer yourself—and from having to handle a dangerous, acidic chemical.

Whatever chemicals you add to your water don’t just spread evenly on their own. You’ll need a reliable, powerful, and energy-saving pump like the 2 HP Energy Star Variable Speed In Ground Blue Torrent Cyclone Pump to make sure all your water is treated. Plus, it comes with a lifetime warranty, is eligible for rebates, and pays itself off in under a year. According to customer Dave Schmidt, “My pool has never looked cleaner!”

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The Breakdown: Cyanuric Acid and Chlorine

In order to fully understand how cyanuric acid functions in your pool, we first need to cover how chlorine usually reacts in the sun. Warning: we’re about to throwback to chem class again. When you put chlorine without cyanuric acid (that is, unstabilized chlorine) in your pool, its chemical makeup transforms to a compound called sodium hypochlorite, which is made up of ions. When ultraviolet rays (thanks to our pal the sun) hit those ions, they break apart and render your chlorine ineffective. In fact, in as little as under twenty minutes of exposure to the sun, your chlorine could be 50% less effective. And it only gets worse from there.

Unless you have an indoor pool that is completely hidden from ultraviolet (UV) rays, adding cyanuric acid is absolutely essential—and much cheaper than wasting massive amounts of ineffective chlorine. It’s one of the many reasons it’s important that you choose the right chlorine for your pool and circumstances. 

Cyanuric Acid, Do You Even Lift? 

For a liquid or granule, cyanuric acid is surprisingly powerful, and can do the heavy lifting chlorine simply cannot achieve on its own. Because unstabilized chlorine is destroyed so quickly by UV rays, outdoor pools without cyanuric acid don’t have a fair shot at being properly sanitized. In other words, any swimmers in your pool will be doing laps among microscopic swimmers—bacteria that may have the ability to make you sick. 

Since cyanuric acid prevents chlorine from breaking down in your water, it allows it to destroy bacteria three to five times longer as it would without CYA. That means three to five times less of a charge on your chlorine bill, and three to five times less hours of chlorine upkeep required. The math is working out in our favor here.

The Con of Cyanuric Acid 

Okay, there is some bad news here. Cyanuric acid is an awesome, essential chemical. But like any solid long-term relationship, it’s all about balance. And oddly enough, at the same time that cyanuric acid allows chlorine to work, it can also hinder it, albeit to a smaller degree.

Say this phrase five times fast: oxidation reduction potential. Thankfully, it’s also abbreviated to ORP. Basically, ORP is a figure that shows you how well your chlorine is working. Regardless of how much chlorine you put into your pool, cyanuric acid reduces ORP. Plus, if you add too much cyanuric acid or your levels rise too high over time, your chlorine will be rendered completely null. That means no working chlorine, no working cyanuric acid, and a lot of wasted money and time.

I know what you’re thinking. Cyanuric acid is essential for chlorine to work, right? But it also can stop it from working entirely? That’s a lose–lose situation. But don’t worry: there’s a way to not worry about this issue at all. Basically, the last chemical you ever want to get trigger happy with is cyanuric acid. If you need to increase it, increase it. But once you have the right amount in your pool, you rarely need to add more—this chemical is known to maintain fairly consistent levels over time. 

And what if you’re adding in trichlor or dichlor, and don’t have as much control over the levels of cyanuric acid in your pool? Well, these are formulated to have just enough cyanuric acid to stabilize the chlorine with which it is mixed. You won’t have to deal with super spiked levels over time. And if you do, all you need to do is dilute your water by giving your pool a partial drain.

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Cyanuric Acid Levels—Right On The Money

I get it—you’ve got the background down, and now you want the details. As with any pool chemical levels, we turn to the health authorities to get it just right. At the end of the day, achieving the perfect chemical balance is all about safety.

According to the World Health Organization, the cyanuric acid in your swimming pool should never be above 100 parts per million (ppm). To take that one step further, I’d recommend that you keep your cyanuric acid levels around 50 ppm. This will keep your chlorine working at its optimal level—that means better control over algae spores and cloudy, murky water. Any problems that stem from a lack of proper sanitation can be expensive to fix, so by maintaining these levels you’re also saving a ton of money. Booyah.

How to Lower Cyanuric Acid in Your Pool

If your cyanuric acid levels are marked as too high on your next pool water test strip, it’s time to figure out just how they rose. The most common reason cyanuric acid levels spike are due to the use of stabilized chlorine over a long period of time. If you’re not sure whether your chlorine is stabilized, check the packaging for the following cyanuric acid-based chemicals: trichloroisocyanurate, potassium dichloroisocyanurate, or sodium dichloroisocyanurate. Turns out your chlorine is stabilized with cyanuric acid? Switch between stabilized chlorine and an unstabilized chlorine to prevent the levels from rising too quickly again.

But in either case, you’re going to have to partially drain your pool in order to lower your cyanuric acid. This means that you’ll need to rebalance your chemicals once you fill that pool back up, which you should do immediately.

It’s also a great idea to give your pool walls a nice brush to dislodge any cyanuric acid that might be clinging to your pool walls, as well as give your filter a healthy backwash to expel any sitting cyanuric acid from your greater circulation system.

This about to get a little scary, but another case in which you might need to lower your cyanuric acid levels is if your pool is contaminated with the parasite cryptosporidium. In this case, the best way to kill this nasty, harmful bacteria is to lower your cyanuric acid to below 15 ppm, and give your pool a triple dose of fast-acting pool shock. Instead of backwashing your filter, it’s better in this case to replace the filter media entirely. Yeah, yikes.

To drain your pool, you want a powerful, reliable, and heavy-duty submersible pump like the BLACK+DECKER 1500 GPH Automatic Submersible Pump. It works on its own to detect water up to 1/8 inch and comes with a whopping 30 ft discharge hose and 25 ft power cord.

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How to Increase Cyanuric Acid in Your Pool

Remember, the only time you’ll actually need to separately add cyanuric acid to your pool is when you’re using unstabilized chlorine. Stabilized chlorine like dichlor and trichlor have cyanuric acid already included, and we love them for it. However, if your levels rise significantly while using stabilized chlorine, you do have the option of switching to unstabilized chlorine and adding your cyanuric acid separately, which will help you maintain better control over how much is added to your pool with each chlorine dose.

What You’ll Need to Add Cyanuric Acid to Your Water

Other than cyanuric acid itself, you’ll need to gather up a few essentials to add it the best way to your pool:

- Safety goggles

- Acid-resistant gloves

- A large bucket

- Warm water

How to Add Cyanuric Acid to Your Pool—In 5 Steps 

This chemical has the capability to damage your filter and your pool liner, so this method is the safest way to add it to your pool.

1.     First, fill your bucket with about two and a half gallons of warm water.

2.     Next, put on your safety gear. You’re about to handle an acid—so safety is key.

3.     Add a dose of cyanuric acid to the bucket. You’ll want about 13 ounces of cyanuric acid to gain 10 ppm in a 10,000 gallon pool. Make sure you know the size of your pool and your current cyanuric acid levels—and check the measurements your manufacturer recommends, too.

4.     Pour the contents of the bucket directly into your skimmer. Since the cyanuric acid is diluted and your skimmer is more receptive to its acidic nature, this method will protect your pool.

5.     Run your pool pump for the proper daily runtime, which is usually around eight hours. This will circulate the chemical evenly across your pool water.

Master Maintenance Moving Forward

The best way to maintain your cyanuric acid? Well, it’s certainly not avoiding testing your water and hoping that it all works out. Any responsible DIY pool owner needs to regularly check in on their water levels to ensure it’s at optimal chemical balance, and cyanuric acid is just one of those chemicals. It’s recommended that you test your pool at least every week. So that’s your homework—sorry about that.

Since we’re thinking of the future, remember that as of 2021, the switch to variable-speed pumps will virtually be federal law. Thankfully, the Blue Torrent 2 HP Variable-Speed Pump is ultra-powerful, comes with a warranty, is eligible for rebates, and pays itself off in under a year by energy saved. As customer Robert Tafoya says, “Pump works quietly, efficiently, and is easy to install.”

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Keep It Stable! 

You’ve got a great head start—and that’ll take you far. Now the cyanuric acid in your pool is at the perfect level, and it’s going to stay that way for a pretty long time, unless you have a major storm rolling in. And although chemical balance can cause a pool owner to seriously scratch their heads, this part of your chemical arsenal couldn’t be more crystal clear—and it’ll help your water stay that way, too. Enjoy.


This article explains how you can backwash your pool filter efficiently. Want to know how to clean the bottom of your pool? Read more here.

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