Full Guide to Proper Cyanuric Acid Usage for Pool Owners

We will cover in this article all you need to know about the proper cyanuric acid usage in your pool.

Careful maintenance is a must in keeping your family pool safe. Aside from regular pool cleaning, pool maintenance also involves making sure that the water quality is safe for use. 

Regulating swimming pools’ water quality involves chemical usage to kill bacteria and other harmful organisms and prevent its growth. 

Cyanuric Acid Usage

Cyanuric acid is one of the most common chemicals used in pool maintenance. In this article, we will cover all you need to know about the right cyanuric acid usage in your pool. Let’s get started.

What Is Cyanuric Acid?

In the swimming pool industry, the most common knowledge regarding cyanuric acid is that it shields chlorine against sunlight’s UV rays. But before we talk about how cyanuric acid helps chlorine, we need to know a little more about the process of chlorination. 

When you put chlorine in water, they interact with living organisms like bacteria. They destroy the cell membrane, effectively killing the organism’s cells, thus keeping the pool clean.

When you put chlorine in water, they interact with living organisms like bacteria.

After this chemical interaction, the used up chlorine molecules won’t be able to deal with other organisms. Those chlorine molecules that are still available for destroying harmful organisms are called free chlorine. Maintaining proper free chlorine levels is a must to keep your pool hygienic.

According to studies, the UV rays from sunlight affects the free chlorine in the swimming pool. When free chlorine molecules are hit by sunlight, they turn into gas as they absorb energy and escape into the atmosphere. In just two (2) hours, sunlight can remove up to ninety percent (90%) of your pool’s free chlorine molecules. 

Due to this chemical interaction, the creation of a pool stabilizer or chlorine stabilizer is needed. One of which is cyanuric acid.

How Does Cyanuric Acid Work?

Cyanuric acid works by acting as a sun barrier or sunscreen for free chlorine molecules.

And in order for us to understand better how cyanuric acid works, we need to dabble a little in chemistry. This knowledge will also aid in answering some of the most asked questions about chlorine and CYA.

Cyanuric Acid

Cyanuric acid, or CYA, is a chemical compound with a formula of (CNOH)3. The chlorine elements form a weak chemical bond with the three (3) nitrogen atoms of CYA. This chemical bonding leads to what we call a stabilized chlorine.

Using stabilized chlorine has both good and bad sides. The good side is that a stabilized chlorine (since it is shielded from the sun) can last up to eight (8) times under direct sunlight. 

But since the chlorine atoms now have a bond with CYA, it now has slightly weakened sanitizing and disinfecting abilities. This chemical bond reduces the rate at which chlorine can kill the harmful organisms in the pool. The reduction of chlorine’s cleansing ability is evident when you conduct an oxidation-reduction potential (ORP) test.

To compensate for this negative effect, maintaining proper chlorine levels and CYA levels is a must. We will talk about maintaining cyanuric acid levels later in this article.

Do You Need To Use Cyanuric Acid?

That answer to that question is “yes” if your pool is an outdoor type and “no” if it’s an indoor pool type. 

Cyanuric Acid Usage

Remember that the purpose of cyanuric acid is to protect chlorine in your pool from sunlight. So it would not make sense to use cyanuric acid in your indoor pool. Spas and hot tubs also do not need cyanuric acid.

Aside from the benefit of increasing the lifespan of chlorine, using cyanuric will help you save money. Imagine needing to refill your pool chlorine every forty-five (45) minutes because it immediately escapes into the atmosphere. Costly and tedious, we don’t want that.

How To Use Cyanuric Acid In Your Pool?

Now that we’ve concluded that you need to use CYA and your pool is an outdoor type, the next question would be how to use CYA in your pool.

The CYA application is pretty straightforward, but first, you need to have these materials and tools on the list below. 

  • Cyanuric acid
  • A bucket
  • Acid-resistant gloves
  • Safety goggles
  • The product manual/instructions
  • Warm water

Just a friendly reminder, as an acid, cyanuric should be handled with extra care. Keep out of children’s reach.

To start the application of CYA, wear your safety goggles and gloves. Then, half-fill the bucket with warm water. Then to achieve the right cyanuric acid levels, check the product manuals on the mixing ratio. One of the rules of thumbs in applying cyanuric acid as a pool stabilizer is a 10ppm concentration would be adding thirteen (13) ounces per ten-thousand (10,000) gallons of water. 

Turn on your pool pump and slowly pour the mixed solution into the skimmer. Wait and let the pump circulate the CYA into the water for you.

You might think that applying CYA is enough. But maintaining proper cyanuric acid levels is needed to ensure that the pool water not at risk.

The Dangers Of Improper Cyanuric Acid Level

Due to the benefits of using CYA, you might think that applying more will give better results. But having high levels of this acid can adversely affect the quality of the swimming pool water and the effectiveness of chlorine. 

Cyanuric Acid Usage

Lowers The Effectiveness Of Chlorine

From what we’ve talked about earlier, using CYA lowers the effectiveness of chlorine as a disinfectant. So why are high CYA levels bad for chlorine effectiveness?

Remember that what we need to disinfect the pool water effectively is free chlorines. And to have free chlorines, we must first overcome the chlorine demand and reach the pool water’s breakpoint chlorination. 

To answer what chlorine demand is, let us use an example. Imagine a pool was filled with a batch of fresh water. The introduced water naturally has metallic elements, organisms, and other minerals. 

Chlorine demand refers to the concentration needed to clean the initial condition of this water. Breakpoint chlorination refers to the point where the chlorine demand was met and where residual free chlorine starts to become available. 

Now let us start putting CYA into the pool water. As you increase the CYA levels, the effectiveness of chlorine diminishes. By how much? According to research, in order to form free chlorine (aside from reaching breakpoint chlorination), you’ll need to exceed 7.5% of the CYA levels.

So let’s say that the CYA levels of your pool water have 100 ppm (parts per million), then chlorine concentration should exceed 7.5 parts per million. So how much chlorine would that mean for a pool? For a 10,000 gallon pool, that would mean adding 10 ounces of chlorine every 16 hours.

Affects Pool Water Quality

Another bad impact of high levels of cyanuric acid is the increased cyanurate alkalinity of water. Cyanurate alkalinity is dependent on cyanurate, salts that are produced by cyanuric acid.

When cyanurate alkalinity reaches a certain threshold, it will contribute to the total alkalinity of the water in your pool. High alkalinity will result in the forming of water scales, clogging of pumps and filters, and cloudy pool waters.

May Affect Chemical Automation

For those who have an automated chemical input system, high levels of CYA can also interfere with the sensors of your pool system, specifically the ORP sensors.

ORP stands for oxidation-reduction potential and refers to the measurement of sanitizer effectiveness in water. ORP is measured in millivolts (mV) because it gauges the ability of a substance (in this case pool water) to oxidized or chemically reduce other substances.

ORP sensors detect the conductivity of water. If the water has high levels of CYA, the ORP sensor will have a hard time detecting residual free chlorine attached to CYA. To address this issue, adjusting the calibration of sensors can help.

International Standards On Cyanuric Acid

The Centers for Disease Control and Prevention (CDC) recommends chlorination to disinfect pools, spas, and hot tubs. According to the CDC, it is the responsibility of the home pool owners or pool industry leaders to regularly check and maintain their pool. Bearing this responsibility is a must because it involves the health of you and your family.

If using cyanuric acid, a chlorine stabilizer, or products with cyanuric acid (products labeled as dichlor or trichlor). They also recommend maintaining a pH level of 7.2–7.8 and a free available chlorine concentration of at least 2 ppm in pools. The CDC does not recommend using cyanuric acid or chlorine products with cyanuric acid in hot tubs/spas.

Fecal Incidents and Cyanuric Acid Usage

The Centers for Disease Control and Prevention (CDC) raises a warning about cryptosporidium. Cryptosporidium or “crypto” is a parasite covered with a special protective layer against chlorination. This parasite is the leading cause of waterborne diseases in the United States. 

There are three (3) main ways that you can get infected with crypto: in a pool, cattle, and childcare.  All of these factors are linked with fecal matter and it is believed that the main source of “crypto” is animals (domesticated or wild). But we will only focus on the pool aspect of transmission. 

To prevent transmission of “crypto”, people with diarrhea should not use the swimming pool. In the case of fecal discharge in the pool, it is recommended to completely drain the pool and clean it completely including the pipes and pumps. Then pump in fresh water after cleaning.

During normal pool operation, a weekly hyper chlorination is recommended by the CDC to remove possible “crypto” parasites in the pool. Since cyanuric acid weakens the effectiveness of chlorination, a high level of CYA will hinder the removal of “crypto” parasites. That is why it is advised to lower the CYA level at 15 ppm by the CDC during hyper chlorination.

A cryptosporidium infection usually goes away after a week. But for those who have a weak immune system, the infection can become life-threatening if not immediately treated.

How To Maintain Cyanuric Acid Levels In Your Pool

The first step in maintaining the levels of cyanuric acid (CYA) in your pool is to measure the current level of CYA. This will give you a baseline on whether you need to increase or lower the CYA. Depending on the state guidelines you are in, it is advised not to exceed a 100 ppm CYA level.

The easiest and cheapest way to check the CYA level of your pool is by using test kits. Usually, the test kit includes CYA test strips, pH level tests, and chlorination tests.

To use the test strip for CYA, submerge the strip into the water as instructed in the test kit manual. Wait for the test strip to change color and compare it to the color graph in the manual. 

If the test result shows low CYA levels, then you can simply add to meet the needed chemical concentration.

If the test results show that you have a high CYA level, then check first the chlorine product you are using if it already has CYA. If the product label has “dichlor” or “trichlor” in its chemical name it already has CYA. Stop adding these into your pool, introduce freshwater into the system, and use pure chlorine.

For pools with very high levels of CYA, it is advisable to completely drain the water in the pool and replace it with fresh water.

Frequently Asked Question

Do indoor pools still need cyanuric acid (CYA)?

No, the purpose of using CYA is to protect chlorine from sunlight. Since an indoor pool is not exposed to the sun, 

Should I use cyanuric acid (CYA) in spas or hot tubs?

No. The CDC does not recommend using CYA in spas or hot tubs.

As pool owners, having a great understanding of knowing how to maintain the pool is a must. It is the key to safe pool usage and avoidance of unnecessary costs.

You are now fully equipped in using cyanuric acid for your pool. So, go ahead and test the CYA levels of your pool. We would love to hear from you! Comment down below to let us know your thoughts.

Are you still in the mood to learn more about pool care, maintenance, and design? We got you! I listed below some of our interesting pool topics that will definitely excite you!

Click here to know about the Chlorine types and brands that are best suitable for your home pool.

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About the author

Brian Anderson

The rather dry pool world out there is in need of some passion to make it shine. With the help of my son Ruben and his wife Maria our mission is to help you create the favorite spot of your house - your pool.

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