How to Raise Cyanuric Acid in Pool

How to Raise Cyanuric Acid in Pool

Cyanuric acid (CNOH)3 is a pool conditioner and stabilizer that plays a crucial role in your swimming pool. It prevents chlorine from breaking down and dissipating fast under direct sunlight.

Cyanuric acid (CYA) works by attaching to the chlorine molecules and acting as their sun shield by absorbing the sunlight. If CYA is too low, it will not be effective enough at shielding chlorine from the sun. Therefore, the chlorine will break down fast and will not keep your pool sanitized.

Although cyanuric acid will not dissipate naturally like other pool chemicals, dilution from rainwater, pool leaking, and splashing can reduce its levels. Therefore, it is crucial to know how to restore it to the optimal level.

What’s the Optimal Level of Cyanuric Acid in Pool Water? 

The optimal CYA levels for your pool will depend on whether you are using a saltwater or chlorine sanitization system. For chlorine-based systems, the optimal level is 20 to 50 ppm (parts per million). However, for saltwater pools, it should be between 60 and 80 ppm.

A higher level than the recommended does not increase the stabilization effect of CYA. Instead, it causes chlorine to lock in, which makes it ineffective at killing bacteria. 100 ppm is the absolute maximum, and you should only get it to this level if you live in areas that get lots of direct sunlight.

Lower levels than 20 ppm mean that the chlorine still dissipates fast under the sun and will break down before it cleans the pool effectively. Also, if you have a low CYA level, you must keep adding more chlorine to ensure the water is sanitized, which is expensive and time-consuming.

How to Test Cyanuric Acid? 

Test strips provide the most straightforward method for testing cyanuric acid levels in pool water. However, it is vital to make sure you get those with a chemical formulation that allows them to detect CYA in pool water, such as the Varify Pool and Spa Test Strips.

All test strips come with more specific directions. However, the basic process entails dipping them in the water for a few seconds to change color and then checking it against the provided scale to determine the CYA level.

Besides test strips, you can also do a liquid turbidity test. Although the process might be longer and a little complicated, the results are often more accurate. With this method, you need to take a water sample from your pool and mix it with the provided compounds. However, any kit you buy will come with clear directions on what to do.

2 Effective Methods for Raising Cyanuric Acid in Pool 

There are two main methods of raising CYA in pool water: adding pure cyanuric acid or stabilized chlorine. With both options, you need to make sure the pH and alkalinity levels are optimal before starting.

Method 1: Use Stabilized Chlorine

Stabilized chlorine combines chlorine with cyanuric acid. It comes as either sodium dichlor or sodium trichlor, and you can get it in granular, powder, liquid or tablet form.

You should use stabilized chlorine when you hope to raise the CYA level by under 10 ppm, as it will not be very effective when you want to make a more substantial increase.


Step 1 – Test CYA Level and Balance Pool Chemistry

The first step is to test the CYA levels and balance out other things like the pH and alkalinity. Keeping the pool chemistry balanced makes the job easier for you as you will not need to restore these other vital elements afterwards.

Step 2 – Determine How Much Stabilized Chlorine You Need

Remember that the optimal chlorine levels should be between 1 and 3 ppm, while the CYA levels should be 20 to 50 ppm. Hence, you need to determine how much stabilized chlorine you need to use to attain the optimum level for both compounds.

Step 3 – Add Stabilized Chlorine to the Pool

Next, measure the amount you need and add it to the pool. You often have to mix powder and granular chlorine with water first, but you can add liquid chlorine directly. You can either pour the chlorine on the skimmer or along the pool’s perimeter.

Step 4 – Allow Water to Full Cycle Before Retesting

Allow the water to fully cycle, which takes around 6 hours for most pools, before testing the CYA and chlorine levels again. If they are still not optimal, you should repeat the process.

Method 2: Add Pure Cyanuric Acid

When your CYA levels are too low, you should add pure cyanuric acid to bring them back to optimal levels. With this method, you will not need to add any chlorine, but you will probably only use it once or twice at most every year for most pools.


Step 1 – Test CYA Level

Always start by testing the cyanuric acid level to determine how far you will need to raise it to get to the optimal point.

Step 2 – Measure the Right Dose

With the measurements you get above and the provided instructions on the CYA packaging, you should now measure the amount you need to use. Typically, you need at least 13 ounces of pure cyanuric acid to raise the level by 10 ppm if you have a 10,000-gallon pool.

Step 3 – Dilute the Acid with Water

Now you need to dilute the measured CYA with water (preferably warm water). Follow the manufacture guidelines to determine the water to cyanuric acid ratio to use.

Step 4 –  Add Solution to the Pool

The next step is pouring the CYA into the pool. Here it would help if you poured it directly into the skimmer for fast and even distribution.

Step 5 – Give it Time to Work and Retest

The last step is to allow the solution enough time to work before retesting. At least 6 hours should be enough, and if the level is still low after retesting, you should repeat the process until you raise it adequately.

Read more: How to Lower High Cyanuric Acid in Pools

Bottom Line 

You need to keep the cyanuric acid level at optimal levels to protect your free chlorine from the sun to ensure it keeps sanitizing the pool water effectively.

Luckily, raising CYA levels is relatively easy as you only need to add stabilized chlorine or pure cyanuric acid. Also, remember to keep testing the levels regularly to ensure adequate pool water sanitization throughout.

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