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What is Cyanuric Acid (Stabilizer)?

What is Cyanuric Acid (Stabilizer)?

Cyanuric acid (CYA), also known as stabilizer, is a stabilizing chemical used to help chlorine used in pools to be less affected by sunlight and last longer. Cyanuric acid with the formula 1,3,5-triazine-2,4,6-triol (CNOH) 3 is a chemical compound. 

Since cyanuric acid and cyanide are not related, it is suitable for use in swimming pools in terms of health. Cyanuric acid allows the chlorine added to the pool to last longer without being under the influence of sunlight. The most important reason for this is that trichloroisocyanuric acid and di-chlorine, which are in the form of granules, powders or tablets, are the forms of chlorine from which cyanuric acid emerges, which tends to dissolve slowly in water and can last longer in water. What distinguishes cyanuric acid from the others is that the chlorine substance continues to exist in water even though it evaporates into the air after completing its task in water. When it comes to disinfection, the stabilizer takes the leading role. Its use in indoor pools is prohibited. For this reason, it is widely used in open pools in our country.


The function of the stabilizer is to ensure that chlorine stays in the pool water longer and that a more effective oxidation and disinfection process takes place in the pool water. Cyanuric acid should be between 20 - 50 ppm in open pools. Otherwise, the growth of microorganisms such as viruses, bacteria and algae that cause serious diseases in pool water cannot be prevented. If the cyanuric acid balance is not maintained in the pools, you will both risk your health and have a green and dirty pool.

Changes in the level of cyanuric acid in the pool water begin to occur through chlorine in powder or tablet form, which is added to the pool periodically. However, in order to avoid a problem, the stabilizer rate in the pool water should be monitored. When it exceeds the expected limit, chlorine or salt chlorine generators that do not contain stabilizer must be activated. When the cyanuric acid levels in pool water reach 100 parts per million, the pool water gets into serious trouble and the question "How to reduce cyanuric acid?" starts to come into play.

Although cyanuric acid is an important substance in the disinfection work with chlorine, the high concentration of the stabilizer substance over time causes chlorine lock-up, a hazy appearance in the water and gradually increasing chlorine consumption. For this reason, they try to prevent the dispersion of chlorine without being affected by the ultraviolet rays of the sun with cyanuric acid to bond with free chlorine in pool water studies. Excess cyanuric acid, which is used extensively in outdoor pools, begins to eliminate the effectiveness of chlorine in the fight against bacteria in the water.

Cyanuric acid reaching 100 ppm and above in pool water causes an event called chlorine lock-up. After reaching this level, the chlorine thrown into the pool has no meaning. At this stage, the stabilizer in the pool water traps the added chlorine. At such a point, all that needs to be done is to drain most of the pool water and add fresh water to the pool. Thus, the cyanuric acid ratio is brought to normal levels.


The use of cyanuric acid in indoor pools is prohibited. For this reason, it is especially used in open pools. To give examples of pools where cyanuric acid is used:

  • Children's Pools
  • Wave Pools
  • Jumping Pools
  • Infinity Pools
  • pool types such as pools can be given as examples.

It is especially suitable for use in newly filled pools or in all pools for a few months a year. The stabilizer (cyanuric acid) added to the pool water should be measured regularly and periodically. Chlorine with cyanuric acid stabilizer stays active as a disinfectant in the added water for a certain period of time. Despite its volatility, it causes accumulation in the added water and can easily exceed the standard values. If you use stabilized chlorine in your pool, it will be useful to have the cyanuric acid level measured periodically once a week. So, how is cyanuric acid measured? Several methods can be used to measure cyanuric acid. The most preferred method is to partially drain the pool and refill it with fresh water. The criterion for this method is that it takes time to determine the extent to which chlorine is locked in. It is sufficient to partially empty the pool and refill it.


In order to reach ideal values in pool water, various chemicals must be added in a certain balance and constantly controlled. Contrary to what is thought when these chemicals are used in pool water, they do not harm human health. In fact, by keeping the required amount, it prevents the destruction of various microorganisms that arise due to use and prevents the spread of elements that threaten human health such as bacteria and viruses. Determining the ideal values for pool water and protecting such chemicals with accurate measurements, the quality of the water should be brought to ideal levels. Thanks to the chemical technology that continues to develop today, water quality is also increased without harming the environment and people. Cyanuric Acid Degree expresses normal values when it is between 20 - 50 ppm in open pools. Cyanuric acid is of great importance for pool maintenance.

Pool water should be tested and analyzed before using pool chemicals. One of the biggest roles in pool water chemicals belongs to the pH value of pool water. If the pH value is below 7.0 ppm, abrasions will occur in the pool joints as it will be acidic. At the same time, pool handrails also melt. This rate, which also negatively affects human health, causes burning in the eyes of swimmers and rashes on their skin. The pH value of pool water is expected to move between 7.2 and 7.6, which are ideal values.

The amount of cyanuric is also an important substance in disinfecting. Always have a table where you can see the amount of chlorine according to the acidity ratio. As the amount of cyanuric acid increases, the effectiveness of chlorine decreases. In order not to be affected by this negativity, you should closely follow the developments with the calculation table. When you need to reduce the cyanuric acid content, it is often sufficient to add water. However, in cases where the cyanuric acid ratio exceeds 100 ppm, a complete change of the pool water is a permanent solution. Pool water becomes cloudy as a result of using more stabilizing chemicals than necessary. What is the importance of using pool maintenance chemicals?

Routine maintenance of pools used every month of the year is mandatory. This maintenance activity, which is mandatory in terms of not harming human health, must be carried out by professionals. . Some damages may occur as a result of maintenance work done by people who do not have knowledge and experience in chemicals. Pool maintenance has a lot of criteria in itself. The type, quantity and quality of chemical maintenance materials are among the main criteria.


While pool maintenance is extremely important for human health, its cleaning requires a special sensitivity. As well as cleaning the water, controlling the pool joints is also important to prevent ceramic spills. In-pool lighting and changes are among the issues to be considered.  Pool side gratings should be checked, and if there are worn gratings, they should be replaced to prevent an accident. The pool pump is also one of the issues that are sensitive to maintenance. Pool sand filter control is another item that needs to be done. If deterioration has occurred in the pool filter sands, quartz sands must be replaced. So, how is pool maintenance done?

Precipitant application is made in maintenance works that should be carried out step by step. At this stage, you should first measure the pH value of the water. It is in the range of 6.8-7.2 is a point of attention. After adding the precipitant to the water, keep the system running for at least 4 hours. At the end of the fourth hour, close the pool and let it rest. Take care to use as much as necessary so that the pond is not turbid.

  • In order for the shock chlorination to have the expected effect, the pH value must reach the range of 7.0-7.4. For shock chlorination, you should determine at least 4 times the average daily dose.
  • What is important here is that you do not measure after shocking. You will encounter misleading results. At this stage, the pool should not be used before 12 hours have passed.
  • Run your test device that you will use during the measurement at least 4 hours later.
  • Pool chemicals have a certain time of use. When you have more than one chemical to dispose of in a day, make sure that there is a 4-hour interval between each one.
  • Increasing the rate of cyanuric acid (stabilizer) will cause the disinfecting effect of chlorine to disappear.
  • Cyanuric acid is added to water in the form of powder granules or tablets. Thanks to this substance, chlorine will be able to stay in the pool water longer without making the effect of the sun's rays felt and will help to create a more effective oxidation and disinfection in the pool water. Fresh water is added to the pool to reduce the cyanuric acid level. If the cyanuric acid level will drop from 80ppm to 40ppm, it is essential to refresh the pool water by half. In cases where cyanuric acid exceeds 100 ppm, all water must be replaced immediately.
  • Hypochlorite (powder chlorine without stabilizer) should not be used when the alkalinity value is above 120 ppm in order not to cause turbidity in the water.
  • The use of liquid chlorine and calcium hypochlorite is effective in increasing the pH value of pool water. Dichlor is a substance that does not affect the pH ratio. The use of tablet chlorine can affect the pH value of the water downwards.
  • At a pH value of 8 and above, chlorine activation in water is greatly reduced. At a pH value of 7 and below, chlorine activity accelerates and chlorine is rapidly depleted. The range 7.2-7.6 represents an ideal pH value.
  • If the chemical addition of a pool is done manually, there should not be a swimmer in the pool. Evening hours are suitable for this work.
  • The amount of alkalinity is very important, especially when applying pH reducers. In 100 liters of pool water with low alkalinity, 1 kg of pH reducer lowers the pH value by 0.2 degrees.
  • It is incorrect to use a high amount at the same time in the pH reduction process. If you need to use more than necessary, it would be best to use half of it on the first day and determine the additional amount after re-measuring the next day.
  • You should pay attention to the amount of algaecide/preventative to avoid foaming in the water. Algaecides do not disappear in water like chlorine. The rate that increases with excess is reduced only with the addition of fresh water.
  • For in-pool cleaning, 2.5 kg of algaecide is used for a 100-ton pool when the pool is empty. After the algaecide is diluted, it is carefully applied to the entire surface with a brush.
  • Turbidity and discoloration may occur in pool water from time to time. In such a case, shock chlorination, continuous filtration and precipitation are applied. Metal ions such as iron, copper and manganese color the water.
  • If a swimmer enters the pool without showering, he/she pollutes 20 tons of pool water.
  • The backwashing time of the sand filter is 5-7 minutes. Care should be taken to ensure that the rinsing time is 30 seconds and above.
  • While 1 kg of liquid chlorine is required to reach 1 ppm chlorine level in a 100-ton pool, 200 gr of 56% dichlorine is sufficient.
  • As long as liquid chlorine stops, it loses its active chlorine content rapidly. It is seen to fall below 10% in a short time.
  • One of the most important features of chemicals is that they must be dissolved with plenty of water. Dissolve with plenty of water in another container before use. To avoid a sudden reaction, the mixing container must be filled with water first and then with the chemical. When powdered chlorine is thrown directly into the water, it may cause discoloration on the floor. Powdered acids, on the other hand, can cause corrosion of joint sealants while lowering the pH.
  • You should take care not to touch your skin with the devices you will test and the chemicals you will use. Keep them out of the reach of children.
  • It is important that the pool circulation system is always on. When you need to rest, your preference should be night hours. Never disable circulation during pool use.
  • Your preference in pool filling water should be in favor of mains water. However, if filling with another water, it should not be filled without analysis. Water with very high alkalinity, containing nitrate, iron, copper, aluminum, ammonia above the values are not suitable for pool use. We also recommend that you stay away from softened water so that your ceramic joints do not melt.
  • Liquid chlorine is affected by the UV rays of the sun and disappears from the water in 4-6 hours. In stabilized chlorine, this period is 6-8 hours.
  • If sufficient chlorine level is detected during the measurements but deterioration is observed in the water; pH values should be checked. Cyanuric acid level must be detected.
  • In the process of lowering the alkalinity value, pH-lowering chemicals are applied by different methods. First, the pool pump is stopped. In the second step, the pH reducer is added to the pool in bulk from a single point slowly. After waiting for half an hour, the circulation pump is activated.
  • Take care to take winter precautions in the winter season. Pool water should be drained and disinfected at the beginning of the summer season.


The fastest way to measure cyanuric acid is to test for total chlorine and free chlorine. Free chlorine tests are performed with a test kit. Sample water is taken from the pool where the test will be performed and dpd1 tablet is thrown into the chlorine measurement section. The result is obtained with the melted tablet. In the bound chlorine test, dpd3 tablet is placed in the same section without pouring the sample water from which the result is obtained. After the tablet dissolves, cyanuric acid is determined.

Although the price of cyanuric acid test kits may seem high at first glance, it is much less costly than lost or ineffective chlorine. Those using stabilized chlorine should buy a test kit. On the other hand, those who use non-stabilized chlorine should contact pool professionals. Tests performed by pool professionals take 1-2 minutes and can be done anywhere you want. Since the stabilizer is not depleted, those who use chlorine without stabilizer do not need to measure all the time. It is enough to do it every 3 months. Those who use chlorine with stabilizer should measure at least once a month and keep the value below 80mg/L. When it starts to rise above the specified value, intervention should be taken.


Cyanuric Acid Test Kit is used to measure the amount of stabilizer chlorine in pool water. The kit includes 1 cyanuric acid indicator, 1 test tube, 1 syringe and package insert. It is the most practical measurement tool to measure the amount of cyanuric acid in your water.


The kit to measure the amount of urine and cyanuric acid in the pool is used by following the 4 steps below:

  • Fill the tube in the test kit with 5 ml of the sample water to be tested to the mark line.
  • Add 5 drops of cyanuric acid solution to the same area. Close the cap vigorously and shake for 10 minutes.
  • Take some of the mixture into the syringe with the help of the syringe in the box and add the mixture taken with the syringe into the tube with a black bottom until the blackness on the rope is not visible, so that it is placed vertically on a flat surface.
  • When the black spot disappears completely, the mark on the edge indicates the amount of cyanuric acid in the water in ppm.


First of all, cyanuric acid should be measured. It should be intervened as soon as it goes beyond ideal levels. "How to reduce cyanuric acid?" Let's examine step by step.

  • Step 1; Use a test strip to determine the amount of cyanuric acid in the pool water. After sticking the strip in the water, pull it out and compare the color of the strip with the color chart included in the kit. If the amount of cyanuric acid is above 80 ppm, the amount of cyanuric acid in the pool needs to be reduced immediately. The ideal amount is between 30 and 80 ppm.  In order for the sun's rays to eliminate the amount of free chlorine in the pool water, 40 ppm is considered sufficient.
  • Step 2: Connect a submersible sump pump to a power source. Bring the garden hose over the submersible sump pump according to the drawing you used. Connect the hose connection on the left or right side of the pump. Keep the other end of the hose away from the pool. The water in the pool will drain from the hose and the other end.
  • Step 3; Activate the pump and hang it on the garden hose to feed the pool. Balance the pump with weight to hold it in place while lowering it into 3 inches of water. Monitor the operation of the pump. When the water volume level decreases, move the pump downwards so that the water is always in it during operation. Drain up to half of the pool.
  • Step 4; After turning off the pump, disconnect it from the garden hose. Place one end of the garden hose on the faucet and the other end in the pool. After turning on the water, fill up to the pool limit. The water should come halfway up the skimmer plate.
  • Step 5; Use the test strip for iso cyanuric acid and retest. The result should always be below 80 ppm.