There are many factors which are essential in making sure your pool remains safe for use, including water sanitization, metal content reduction, balancing the water’s pH level, and making sure it remains free of algae.

One such factor is making sure your hard-earned money put into buying chlorine, doesn’t evaporate, leaving your pool full of disease-causing microbes. Preventing this from happening is called pool stabilization, and adding a special compound called pool Cyanuric Acid to the pool makes the magic happen.   

Cyanuric acid, or CYA as it is popularly known, is the de-facto pool stabilizer in the market. CYA is one of the chemicals which help you make your pool swimmable and clean, if you use chlorine as a disinfectant. It helps the chlorine in your pool by making sure that Ultra Violet (UV) rays do not degrade the chlorine content.

In this article, we’ll go into the depth of what is Cyanuric Acid for pools, its benefits as well as the problems associated with excess CYA in pool. We’ll wrap up with the best practices to use pool Cyanuric Acid to keep your pool healthy and safe to swim in.

What Is Cyanuric Acid For Pools?

Time for a small chemistry lesson!

(Note: Maintaining a pool has many chemical requirements, so it’s recommended that you learn a few things about how they work. This will help you understand the reasoning behind expert tips for keeping your pool in shape.)  

The Pool Stabilizer Cyanuric Acid (or CYA) is a benzenoid triazine compound, which implies that it has three carbon atoms and three nitrogen atoms. Many triazine compounds are found in common use, such as disinfectants.

The structure of the CYA allows for three molecules of chlorine to attach to the nitrogen, forming a weak nitrogen-chlorine bond (N-Cl). The weakness of thee N-Cl bond allows for chlorine to let go of CYA when it has something to oxidize or kill. When attached to CYA, however, chlorine is protected from sunlight. Thus, adding cyanic acid in pools acts like sunscreen for the chlorine.

This compound has many favourable chemical properties, but the one most commonly used is the inhibitory effect of CYA on UV rays. UV rays can quickly decompose chlorine into atomic form which makes your pool susceptible to many diseases.

How Does Cyanuric Acid Work?

A pool which is indoors does not generally have much exposure to UV rays, and hence does not require CYA. However, CYA in pools is necessary when the pool is outdoors, and hence exposed to UV rays.

Not adding CYA poses considerable problems, in that unstabilised chlorine evaporates from the surface of a pool, and thus, you would be required to add chlorine to the pool time and again in order to maintain chlorine levels.

A study suggested that within 17 minutes of UV exposure, around half of the chlorine content from your pool goes away, leaving it susceptible to spread diseases and make your pool an algae sanctuary.   

To understand what does pool stabilizer do, we start with life’s elixir – water.

Water contains many ions, including sodium. The sodium from the pool water reacts with chlorine to create a compound called sodium hypochlorite. After the chlorine content transforms into sodium hypochlorite ions, the CYA binds to those ions, preventing them from breaking apart when exposed to UV rays.

This is how it preserves your free chlorine. This allows the protected chlorine to destroy bacteria at least up to eight times longer than it would without cyanuric acid.

How To Use Cyanuric Acid In Pools

The easiest way to add cya to the pool would be to purchase pre-stabilised chlorine, available on the market by the name of stabilized chlorine.

However, this method brings with it the problem of CYA levels slowly increasing over time, which becomes problematic. This would mean that you’d have to reduce those levels (more on that later).

Hence, it is recommended that every time you’re about to thoroughly clean your pool, you should flush the pool, add fresh water, and add the CYA and chlorine separately. This will help you to clearly establish how much CYA you need, and the probability of having to lower cyanuric acid levels is decreased.

One of the most important steps is calculating exactly how much CYA you need. The general rubric to be followed is that to increase 10 ppm of CYA in a 10,000 gallon pool, you’ll need to add 4.1 lbs of cyanuric acid.

How To Add Cya To Pools

CYA is an acid. Hence, it can cause damage to your filter and to your pool. Vinyl liners are especially prone to damage by CYA. Even though some cyanuric acid product labels may instruct you to add it by pouring it straight into the pool or filter, you have to make sure to NOT do it in that way.  

A general guideline would be to add the CYA to warm water, and letting it dissolve in the bucket. This can take some time, ranging from minutes to hours for larger pools. Then, safely add the dissolved content to the pool, and let the pool pump run. It effectively acts as a large stirrer for your pool.  

How Much Cyanuric Acid Do I Need?

The World Health Organization says that you should have no more than 100 parts per million (ppm) of cyanuric acid in an outdoors swimming pool. This figure is based on the premise that pool water gets ingested from time to time, and anything more than 100 ppm can make you sick.

An ideal amount of pool cya hovers around 50 ppm. Keeping aside health and safety issues, going any higher inhibits your chlorine to an extent where it chances algae and bacterial growth. It is important to keep in mind that more CYA doesn’t necessarily correspond to better protection from UV rays, beyond a limit.

If your level climbs above 100 ppm, you may not even be able to read the exact amount on a test strip. In this case, you should go in for fifty percent dilution with tap water, or seventy five percent if the fifty percent tap water does not give you readings.

In the worst case, you should take a sample in to a pool supply store for more accurate testing before you act to lower the CYA level.

How To Monitor Cya Levels

The easiest method to monitor CYA levels is to get pool test strips, which are available online or offline. Traditionally, pH levels have sufficed to address the situation of CYA levels, however, pH levels are much less accurate than pool test strips which are geared specifically for measuring the CYA level.

There are also test kits available, but these only go up to 100ppm, which limits their usability.

It is recommended to monitor cyanuric acid levels regularly, with as much accuracy as you can. High cyanuric acid levels are a cause for concern.

What Problems Does Cyanuric Acid Have?

Too much of everything is bad, and the situation is no different here.

If your pool’s cyanuric acid level is over 50 ppm, you should probably flush it out as soon as you can.

Very high CYA levels will make the chlorine in your pool less effective, and your pool will stay cloudy more of the time.  

Your pool may also develop algae blooms even with high chlorine levels present. These algae blooms are also hard to get rid of in a pool with very high CYA levels.

High levels of CYA are very likely to give you false ORP (Oxidation Reduction Potential) readings if your pool uses ORP to measure the safety and swim-ability of the water. ORP is a voltage measure of the potency of the chlorine in the pool readings.

High CYA also will give you false alkalinity readings, if you test the alkalinity and it is at 100 it is more likely to be actually 70 due to the CYA level being so high.

Why Should I Be Worried About Crypto?

Cryptosporidium, also known as crypto, is a chlorine-resistant parasite, which is found in pools that have had fecal events. This problem is common with pools with small children and babies, whose diapers are not designed for being able to sustain in water.

Crypto can be dangerous, since it is the cause of a number of diseases such as respiratory illness and gastronomical disorders. Further, high CYA levels are directly related to an increase in crypto levels in your pool.

If your pool has alarming CYA levels, you should get your pool tested for crypto, to remain on the safer side.

If crypto is found in your pool, you should immediately lower your CYA levels to less than 15 ppm, and replace your filter so the leftover crypto doesn’t come back into the pool.

How To Lower Cyanuric Acid In Pool

The only sure-fire answer to how to lower cya levels in the pool is to dilute the amount of water in the pool.

Next, you should see whether the problem is because of lingering CYA, found in pool plaster and the calcium scale. If the problem stems from these, you will see a radical increase in CYA levels, right after you flush the pool and add new water. A solution for this would be to change the pool plaster or get rid of the calcium scale.  

If not, then the problem is the water itself. A fix for this is to flush half the pool and add more fresh water, and immediately check the CYA levels. If that doesn’t solve the problem, there might be some remnant CYA in your filter, so it’s a good call to backwash or replace your pool filter.  

The cyanuric acid pool levels need to be monitored at each step, so make sure to keep the test strips or the test kit handy.

How To Balance Cya And Chlorine In Your Pool

It is not always the case that you’ll have to lower cyanuric acid levels, or increase them in an ad hoc manner. You have to take into account the amount of chlorine you must be adding as well.

A recommended level of chlorine in pools is 2-4 ppm, but this is where things get a little complex. You cannot simply add CYA and expect it to work – since it is an assistant chemical to the chlorine, the chlorine levels must be synchronised with the CYA levels.

A balance is crucial to maintain the levels, and for that, there is a golden rule in pool chemistry:

CYA ppm x 0.075 = free chlorine level

For example, if your pool CYA is 40 ppm (which is the ideal amount of CYA), you would require your chlorine levels to be at 3 ppm. This rule will help you make sure that the CYA and the chlorine in your pool work in tandem and not against each other.

Wrapping Up

Congratulations! You now know what is meant by the pool stabilizer cyanuric acid. You also realise how it works on an atomic level, and why it’s important to add it to your chlorine.

You also know the best practices of managing the cyanuric acid stabilizer content in your pool, including how to calculate how much CYA you need to add to the pool in accordance with the pool size. Of equal importance is the relation of the CYA levels with the chlorine content of your pool.

High cya levels can cause many problems, including faulty chemistry readings and in extreme cases, high levels of the crypto parasite.

The tips on lowering the cya levels in your pool will come in handy especially if you are using the pool after the winter season, or it has been kept without care for a long time.

You can now make sure your pool stays disease free, algae free, and clear for many years to come. Your efforts in making sure your pool chemistry is balanced will reap benefits for everyone using the pool!  

Additional Resources:

https://xlpools.com/balance-chlorine-cyanuric-acid-swimming-pool/

https://bioactivenow.com/how-to-test-your-pools-cya-the-easy-way/

https://aquamagazine.com/retail/key-misunderstandings-or-problems-in-pool-water-chemistry-part-i.html

http://blog.orendatech.com/five-things-cyanuric-acid