Swimming Pool Guides & Reviews by Certified Pool & Spa Operator®

How to Use Cyanuric Acid to Stabilize Your Pool

Here’s Everything You Need To Know

Swimming pools require lots of different chemicals in order to stay safe and sanitary for swimmers. There is a separate chemical for everything the water needs, such as sanitizing, balancing, stopping algae, media content management, and more. The chemicals you use also depend on the type of pool you have and the location it is in.

You can’t just depend on one chemical, though. There are “assistant chemicals’ which may need to get added in conjunction with the primary chemical. For instance, one common pool stabilizing chemical is cyanuric acid. The job of this chemical is to stabilize your pool water’s chlorine sanitizer. That way, the chlorine will be able to clean the water for a longer time.

Cyanuric Acid

So, what is cyanuric acid, and how does it work?

It helps if you understand more about the chemicals that you’re pouring into your pool water. Then you can appreciate the chemistry behind them.

Cyanuric acid is a triazine, which is a chemical compound that features 3 carbon atoms and 3 nitrogen atoms. Some examples of triazines include disinfectants, polyurethane resins, and herbicides. Well, cyanuric acid is the primary chemical ingredient used to make these solutions.

Cyanuric acid is often called CYA, and it is used as a stabilizer for chlorine and pool water, or as a pool conditioner. You can purchase CYA as granules or liquid. Some CYA products even contain chlorine shocks and chlorine tablets mixed in.

Combo formulas like these are called stabilized chlorine since the stabilizer and sanitizer are mixed together. This means you don’t need to measure each solution and add them into the pool water individually.

Stabilizer and Conditioner

7 Pounds

Is Cyanuric Acid Worth Purchasing?

CYA can help your pool water tremendously. First, you must realize how badly the sun can impact the chlorine in the water. There are three chlorine types in your pool; combined chlorine, total chlorine, and free chlorine.

Free chlorine refers to the level of sanitizer present in order to clean the water. When chlorine is added straight into your pool water, you’ll have the most sanitizer present. It is also there when you use a salt-water chlorinator to create the chlorine. Either way, you must have chlorine in your water for sanitary purposes. Don’t swim in pool water without it in there.

Combined chlorine refers to the level of sanitizer depleted due to killing organisms like bacteria in the water.

Total chlorine is basically the amount of combined chlorine and free chlorine in the water. Just add these two amounts together to get the total chlorine.

As soon as chlorine is poured into the water of your pool, it turns into ions called sodium hypochlorite. When the sun’s UV rays shine down on these ions, it causes them to split up from each other. The chlorine will then evaporate, causing hardly any free chlorine to be left in your pool water. To give you an idea of how quickly this happens, it only takes 17 minutes for 50% of the free chlorine to disappear from the water after the ions are exposed to UV rays.

CYA kills contaminants much faster than chlorine. To give you some perspective on this, it would take 8 times as much chlorine to destroy the equivalent of what CYA can destroy. Because of this, you can save money by adding less CYA to the water and still get the same results.

CYA will prolong the life of your sanitizer. Meanwhile, you won’t need to spend endless amounts of money on chlorine for your pool.

How Cyanuric Acid Functions?

If there are low levels of CYA in your pool, then it demands more chlorine. This signifies that UV rays from the sun have quickly destroyed the chlorine, so your pool needs more of it. Otherwise, contaminants could easily infect the water and cause trouble for swimmers.

Rather than continuously adding chlorine to the water every hour, you should just add cyanuric acid periodically. After the chlorine is converted into the sodium hypochlorite ions, pour the CYA into the water so it can bind to them. As a result, UV rays won’t cause the ions to break apart. Then free chlorine will be preserved, and bacteria will stay destroyed up to 5 times longer than if CYA was not added.

You’ll want this extra time because the chlorine is hindered by the sodium hypochlorite ions and CYA bonding together. At the same time, the chlorine is stabilized by the CYA.

Stabilizer Conditioner Cyanuric Acid

20 lbs

Disadvantages of Cyanuric Acid

The ability of chlorine to sanitize water is referred to as oxidation-reduction potential or ORP. Millivolts is the unit of measurement for this figure, which reveals the effectiveness of the free chlorine. CYA lowers the ORP of chlorine, no matter the amount that you pour into your pool water.

If excessive amounts of CYA are added to the water, then the chlorine won’t be as effective. This means you would have wasted money purchasing these two chemicals. Not only that, but your pool will still remain dirty.

You’ll want your chlorine to quickly destroy contaminants in the water, so swimmers can stay safe. But the chlorine needs to stay in the water consistently. Therefore, you need to create a healthy balance of CYA and free chlorine in the water.

To boost the level of CYA, just add some more of it to the water. After an adequate amount of CYA has been added, there won’t be any need to add more on a regular basis. CYA tends to stay in the water consistently as time goes on.

The only way CYA levels in the water can lower is by dilution, like from a rainstorm. That is why you should test the CYA levels regularly.

The Right Levels of Cyanuric Acid

According to the World Health Organization, your swimming pool should have a CYA limit of 100 ppm (parts per million). This number was established because they assumed that kids swimming in the water will accidentally swallow some of it. Ingesting excessive amounts of CYA could result in sickness.

For this reason, it is better to keep the limit at about 50 ppm. Higher concentrations of CYA can make the water less safe because it will prevent chlorine from destroying bacteria and algae. So, word of caution, you can’t protect the chlorine from UV rays by adding lots of CYA to the water. It’ll just make it worse.

Once the CYA level is higher than 50 ppm, then algae will likely grow in the water. Furthermore, it will be difficult to balance the chemicals of the water. The sanitization won’t be as effective, resulting in much cloudier pool water.

If the CYA level goes over 100 ppm, the test strip will fail to give you an accurate reading. You’ll have to take a sample of the pool water and go to a pool supply store to have a professional test it out. Based on the results, you can reduce the CYA level accordingly.

The Way to Reduce Your Cyanuric Acid Levels

Once your pool water has been tested, you’ll need to lower the CYA levels if the results showed they were too high.

Are you using a stabilized chlorine in the water? If so, this product has CYA quantities in it. Check the label for the list of chemicals of the stabilized chlorine product. If it contains potassium dichloroisocyanurate, sodium dichloroisocyanurate, and trichloroisocyanurate, then CYA exists in the formula.

If this issue is discovered in your chlorine, then choose new chlorine to use that doesn’t have CYA in it. This will stop the CYA levels from increasing again in the water.

Although, CYA must still be reduced periodically to sustain the effectiveness of the chlorine. If you have slightly high CYA levels, you can lower them by diluting the water of the pool. Simply splash around in the water to reduce the water level and then add more fresh water back into the pool.

If you have severely high CYA levels, then draining the pool and refilling it back up may be your only solution. Remember that CYA can get stuck in your filter so you may need to backwash the filter if you have a lot of CYA in your water.

CYA also exists in calcium scale and pool plaster too. If you refill your pool and still have high levels of CYA, then it means you have CYA remaining in it.

Cryptosporidium Overview

If you have cryptosporidium contaminating your swimming pool, then you must reduce your CYA levels.

Cryptosporidium, also known as crypto, is a type of parasite which can cause someone gastrointestinal illness and/or respiratory illness. If feces were to get into your pool water, then this parasite will follow. You’ll see this type of contamination often in public swimming pools and any public water areas where babies and smaller children go.

Normal levels of chlorine cannot destroy crypto. Once contamination is present, it must be dealt with immediately. The most effective way to destroy crypto is to reduce your levels of CYA to under 15 ppm. After that, your water needs to be hyperchlorinated. Replace your filter rather than backwash it. This prevents crypto from ending up in your water again.

Watch the Levels

You must frequently measure the level of chemicals in your pool water. Otherwise, you wouldn’t know if the water is balanced or not. You must understand pool chemistry to do this right. You also need to schedule times to perform pool maintenance tasks. Stick to this schedule religiously.

Each week you can test the chemistry of the water with test strips. This is a cheap and simple method for testing the water. You can check the levels of free chlorine, pH, and cyanuric acid levels. If you want a better test, then take a water sample and have a professional test it out at a pool supply store. A liquid test kit can also be used too.

It is a good idea to test your water on a weekly basis, if not more. If the water chemistry stays balanced without much rain falling into it, then your CYA levels should stay consistently the same.

Preferably, you’ll want free chlorine that is at least 2 ppm but at the most 8 ppm. When utilizing CYA, you’ll want your levels of free chlorine to be about 7.5% of your current CYA level. For instance, if your swimming pool water has 50 ppm of CYA, then the free chlorine should be anywhere from 3 ppm to 4 ppm. This will ensure the water is cleaned effectively so that algae don’t grow there.

The Way to Add CYA to Your Swimming Pool

When using a stabilized chlorine, such as trichlor or dichlor, it may not be necessary to pour more CYA into the water because CYA may already exist in the sanitizing formula. Try adding stabilized chlorine to the pool water and then test the CYA levels. If these levels are increasing slowly over time, then you’ll have to lower the CYA levels. The best way to avoid this problem is to use non-stabilized chlorine and then separately add CYA to it. You’ll only need to add CYA about 1 or 2 times annually in this scenario.

Remember that CYA is a type of acid, which is something that can damage your pool and/or filter. Pools with vinyl liner are the most vulnerable to this acid. The labels of CYA products may tell you to pour the CYA right into the filter or pool water. Do not listen to these instructions. There is a much safer way to go about this.

Gather warm water, gloves resistant to chemicals, safety goggles, and a five-gallon bucket.

Here is how to add the CYA chemical to your swimming pool:

1) Pour warm water into the bucket so that it is at least 50% of the way filled.

2) Start wearing your gloves and goggles.

3) Pour a little bit of CYA into the bucket. If you want 50 ppm, check the instructions of the product in according with your pool size. Usually, if you want CYA to rise to 10 ppm in a pool that is 10,000 gallons in size, then it’ll take 4.1 pounds of CYA to be added to the pool water.

4) Let the CYA chemical dissolve in the water. You may need to wait anywhere from 10 minutes to a couple of hours. It all depends on the amount of CYA you added. Don’t worry about waiting for hours because the acid won’t damage the surface of your pool as it remains there.

5) After the CYA is totally dissolved, start pouring the liquid from the bucket into the water of your pool.

6) Turn on the pool pump. Keep it running for a couple of hours at least. This gives the pool water a chance to circulate.

7) Maintain moderate CYA levels in your pool water to keep it sanitized properly. Try to protect the water from the sun’s nasty UV rays.

8) Maintaining chemistry in your pool water takes effort, but it’s worth it in the end. It’ll keep your pool healthy and all the swimmers healthy too.

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