All You Need to Know About Using Cyanuric Acid(Pool Stabilizer) for Your Pool

It is a lot of fun to have a swimming pool to cool off during the hotter months of the year but improper hygiene can fast turn it into a nightmare. This means that you need to regularly treat the water in your swimming pool using a process called water chlorination.

This means you add a chlorine solution to the water, which then breaks down into a number of chemical compounds including hypochlorous acid (HOCl) and hypochlorite ions. The sun, however, is a big enemy of this chlorine and can wipe out 75-90% of it in a matter of two hours.

This is where cyanuric acid comes into play. Just adding the chemical isn’t enough to maintain the cleanliness and balance of the pool. You will also need to ensure that it is doing its job and that can be done by adding another chemical to assist it.

Cyanuric acid, a popular pool stabilizer, is one of these chemicals. Its main function is to stabilize the chlorine in your pool so it lasts longer despite the presence of sunlight, making sure that your water is cleaner for longer. The concept of adding another chemical to increase the longevity of one may sound a little confusing so I, Joel Peters, will walk you through this in detail!

What Is Cyanuric Acid? What Is Pool Stabilizer?

In all likelihood, you’d like to know more about this chemical that I am asking you to add to your swimming pool. Cyanuric acid is a chemical compound that contains three nitrogen atoms and three carbon atoms. Its hexagonal ring structure of nitrogen and carbon atoms form weak bonds with chlorine molecules. As chlorine is sold in the form of sodium hypochlorite, it combines with water to form sodium hypochlorite ions.

A type of triazine, it comes from the same family as polyurethane resins, herbicides and disinfectants, but it isn’t the same. This means you can’t interchange their uses.

Cyanuric acid – which can be abbreviated as CYA – is also commonly known in the market as a pool stabilizer, pool conditioner or chlorine stabilizer. This is because it serves as a protection shield for the chlorine in your pool against the harsh effects of the sun. It is classified as “essentially non-toxic” but you should take all the precautions that you would while using any chemical compound.

The chemical is available as a granular solid and as well as a liquid, called sodium cyanurate. However, the most commonly found form is stabilized chlorine like dichlor and trichlor, which has about 50-58% cyanuric acid in formulas. Trichlor is basically chlorine tablets or sticks, while dichlor is popularly known as chlorine shock.

These are popularly known as stabilized chlorine as the stabilizer is already mixed with the sanitizer chlorine, which saves you the trouble of whipping out your measuring mechanism and adding both the components separately.

What Is It Used For?

Before I get to the main uses of cyanuric acid, we need to talk about the chlorine in your swimming pool. There are three types of chlorine in your pool – total, free and combined. Each of these has some particular functions.

The first type is free chlorine, which is essentially the sanitizer that will be cleaning your pool. It is essential for the maintenance of a safe pool environment and is introduced when you add chlorine directly to your water. The other way to create free chlorine in your pool is by using a salt water chlorinator.

The second and third terms are combined and total chlorine. Combined chlorine is the amount of sanitizer that has already been used up in the process of killing bacteria and other germs in your water. Finally, total chlorine is the sum total of sanitizer in your pool, which is the amount you get when you add the free and combined chlorine.

The chlorine transforms into sodium hypochlorite ions when it comes in contact with the water in your pool. However, when the sun’s ultraviolet rays hit those ions, they fall apart, causing the chlorine to evaporate. This means that there will be very little free chlorine left in your pool. All this is when you aren’t using cyanuric acid  — the real chlorine saver!

Not using cyanuric acid can also prove to be very expensive for you. This is because you will need eight times more chlorine to kill the bacteria when you don’t have cyanuric acid added to your pool. Can you believe how much money that is?

Cyanuric acid has a ton of non-pool uses as well. These range from preparation of high-performance magnetic-wire enamels to the manufacture of electrical varnishes, plastics with enhanced properties, flame-retardant resins, and solid lubricants. It is also used for cross-linking and as a curing agent in the manufacturing of plastics and coatings.

Cyanuric acid is used to reduce nitrogen oxides in stationary diesel engine exhaust gases and is also a U.S. Food and Drug Administration-approved feed-grade animal food additive.

How Does It Work?

As we have discussed before, if your pool is not treated with enough cyanuric acid, its chlorine demand will skyrocket. You cannot skimp on the amount of chlorine that is in your pool otherwise it can easily become a breeding ground for all types of germs and bacteria, causing severe harm to all the people who are exposed to your swimming pool.

Lack of cyanuric acid means the unstabilized chlorine will be destroyed very quickly by the UV rays emitted by the sun, leaving your pool extremely vulnerable to contaminants.

If you want to avoid this situation and also not spend tons and tons of money on additional chlorine, simply add cyanuric acid to your swimming pool as directed. Once the chlorine in the water has transformed into sodium hypochlorite ions, the cyanuric acid will jump into action and bind those ions so that they cannot break apart when exposed to the sun’s rays.

This means that your free chlorine is preserved and can kill bacteria for a period that is three to five times longer than it would have otherwise been active without cyanuric acid. This time period is important because while it stabilizes chlorine, the bond between cyanuric acid and sodium hypochlorite ions can also affect the chlorine presence by some degree.

Just make sure that you don’t use it for your indoor pool. This has to do with the basic function of cyanuric acid. It is used to reduce the loss of free chlorine caused by the sun’s ultraviolet rays. If your pool is indoors, it will not be exposed to direct sunlight, making cyanuric acid’s benefit meaningless.

How Can I Add Cyanuric Acid to My Pool?

The use of stabilized chlorine, particularly dichlor or trichlor sanitizers, will ensure that you do not need to add cyanuric acid separately to the pool. This is because, as discussed before, they contain enough cyanuric acid to facilitate its stabilizing function.

There may be a bit of a problem with the cyanuric acid levels over time when you are using stabilized chlorine. If you notice a spike in the levels of the chemical compounds in your swimming pool, you may need to bring those levels down by decreasing the amount of cyanuric acid in the water. To avoid this, it is recommended that you use chlorine that hasn’t been stabilized and add your cyanuric acid separately to have more control over its level.

The benefit of this is that you will only have to add the cyanuric acid once or twice a year if you decide to add it separately from the chlorine. However, keep in mind that cyanuric acid is an acid at the end of the day and can cause some damage to your pool and its filter. This is especially important if you have a vinyl liner as it can be damaged by the use of cyanuric acid.

It is easy to just add the cyanuric acid to your swimming pool or the filter but you should avoid this method to save them from any damage. Instead, use a safer method that will only need a 5-gallon bucket, safety goggles, chemical-resistant gloves (because safety first) and warm water. Once you have collected these items, follow the steps listed below:

  • Fill the bucket with warm water. Instead of filling it to the brim, make sure the water is filled about halfway.
  • Put on your protective gear. This means the goggles and gloves that were mentioned before.
  • Add the recommended amount of cyanuric acid to the bucket. Here, you must make sure you check the product instructions that are specified for your pool type. Generally, about 4.1 lbs of cyanuric acid is enough to gain 10 ppm of CYA in a 10,000-gallon pool.
  • Let the chemical dissolve into the water after pouring it into the bucket. This process could take anywhere between ten minutes to a few hours, completely depending on the amount of cyanuric acid you are trying to dissolve.
  • Once the acid has dissolved completely, pour the contents of the bucket into your pool, without the worry of ruining the pool’s floor.
  • The last step involves running the pump of your pool for a few hours after the cyanuric acid has been poured into the swimming pool. This works to spread the acid throughout the pool without you having to make that effort.

What Is the Ideal Level of Cyanuric Acid in My Pool?

According to the World Health Organization, the levels of cyanuric acid in pool water should not exceed 100 mg/l or parts per million (ppm) in swimming pools where chlorinated isocyanurates are used. This number was arrived at after considering the fact that children are likely to swallow water from the pool as they swim. There has to be a limit, as kids can get sick after ingesting too much cyanuric acid.

However, it is always better if you keep the cyanuric acid levels of your pool around 50 ppm. This isn’t just about the safety aspect but also the performance of chlorine inside your swimming pool. Too much cyanuric acid will reduce the effect of chlorine and cause algae and bacteria to grow in the water. Extra cyanuric acid doesn’t mean extra protection from the ultraviolet rays.

Additionally, if the levels are above 50 ppm, you may be able to see some algae growth or cloudy water in the pool. The cleanliness of the pool will decrease and you may find it difficult to maintain a balanced chemistry in the water of the swimming pool.

Cyanuric levels of over 100 ppm cannot be read on regular test strips so you will have to take a sample of your pool water to the nearest pool supply store to get a more accurate test. Once you find that the cyanuric acid is higher than it should be, you can take the correct course of action.

What Can Happen If There Is Too Much of It?

Too much of cyanuric acid can affect chlorine’s ability to sanitize the water in your swimming pool. This ability, referred to as oxidation reduction potential (ORP), is measured in millivolts and is important as it is an indication of how the free chlorine is working. This ORP is reduced by cyanuric acid in any case but if you add too much of it, it will completely wipe out chlorine’s effectiveness.

This means that you would have wasted your money on two separate chemicals without getting the benefit of either!

You will need to strike a balance between free chlorine and cyanuric acid. It’s easy to add the chemical and once the right amount has been added, it won’t need to be added regularly as it remains at fairly consistent levels in your pool over time. The only way to reduce it is to dilute the water in the pool.

There is also another situation where high levels of cyanuric acid can be an issue. The levels will need to be lowered if your pool is contaminated with cryptosporidium, a parasite that causes respiratory and gastrointestinal illness. Popularly known as crypto, it is usually introduced in pool water through feces and is very common in public pools. It is resistant to regular chlorine levels and can only be eradicated if cyanuric acid is reduced to below 15 ppm.

How Can I Lower Cyanuric Acid Levels?

Check your cyanuric acid levels before you take any steps. If you find out that the levels are high, the first step is to check whether you are using stabilized chlorine. The best way to check this is to look for any of these names on the label of your chlorine – potassium dichloroisocyanurate, sodium dichloroisocyanurate or trichloroisocyanurate.

If you find that your stabilized chlorine is the problem, try switching to chlorine without cyanuric acid as this way you can control the amount of the latter in the pool. If the levels are even higher, dilution is the only option. Bring down the level of water in your pool and top it off with fresh water. If it is even higher, you’ll need to drain the pool and refill it completely.

Cyanuric acid can linger in the pool plaster, filter or other parts of the pool so if the levels aren’t going down, you may have to replace those.

Check the Levels Regularly

The key to maintaining the right amount of cyanuric acid in your pool is to measure the chemicals on a regular basis. This will help you get the right water chemistry and a more hygienic swimming pool.

If you avoid measuring the chemicals regularly, you will not be able to maintain the right balance. This means setting up a pool maintenance schedule and sticking to it! Use test strips to check water chemistry every week to check the levels of pH, free chlorine and cyanuric acid amongst other chemicals.

The ideal levels of free chlorine should be between 2 ppm and 8 ppm and if you are using cyanuric acid, try to keep free chlorine levels at 7.5% of the cyanuric acid level. This translates to a free chlorine level of between 3 ppm and 4 ppm if your pool has 50 ppm of cyanuric acid. This should be able to keep algae away and effectively sanitize your swimming pool!

If you check the chemistry of your water regularly and don’t receive too much rain, the levels of cyanuric acid in the pool shouldn’t change much over time!

Now that you know almost everything there is to know about cyanuric acid and swimming pools, here is your answer to the most frequently asked question – do I need to use cyanuric acid in my pool? There is only one answer to that. Yes, you should use cyanuric acid in your outdoor swimming pool. Without the chemical, the chlorine will get damaged by sunlight and not do an effective job of cleaning the pool. Just keep an eye on the levels and make sure they don’t go above the recommended limits! Have a good pool season!



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