How to Test the Cyanuric Acid Levels In Your Pool

Written by Michael Dean
September 14, 2023

testing cyanuric acid level in a swimming pool

Cyanuric acid (CYA) is a stabilizer used in outdoor swimming pools to protect chlorine from being broken down by the sun’s UV rays. However, as with other chemicals in your pool, keeping the right balance of CYA in your pool water is important.

In this article, I will go over the ideal cyanuric acid levels in your pool before providing a step-by-step guide for testing the CYA levels in your pool with a liquid test kit and a test strip.

Main Takeaways

  • Ideal cyanuric acid levels in a pool are between 30 to 50 ppm; for saltwater pools, this hovers between 60 to 80 ppm.
  • To test the CYA levels in your pool, use a liquid drop test kit or a test strip.
  • To raise cyanuric acid levels, measure and add more CYA according to your pool’s size.
  • To lower CYA levels, you will need to either drain and refill part of your water or use a cyanuric acid reducer.

What are the Ideal Levels of Cyanuric Acid in Your Pool?

As with any other pool chemical, staying within the recommended guidelines of the proper levels for maximum effectiveness is necessary. Too much CYA means your chlorine won’t be as effective, and too little means that your chlorine will break down under the sun’s UV rays.

The ideal cyanuric acid level for a regular pool is between 30 – 50 ppm (parts per million). But there’s a little more to that than you think. Optimal CYA levels scale with your free chlorine levels, which have to hover between 1 – 3 ppm. It’s best to aim for free chlorine levels that are 7.5% of your CYA levels. So, if you have a CYA of 40, you’ll need your free chlorine levels to be 3 ppm.

Recommended cyanuric acid levels for a saltwater pool are higher, falling between 60 – 80 ppm. This is because the sun’s UV rays impact both the salt and the chlorine generated by saltwater generators.

Step-by-Step Guide: How to Test the Cyanuric Acid Level in Your Pool Using a Liquid Test Kit

Here’s a simple step-by-step on how to test cyanuric acid levels in your pool using a liquid test kit. If you don’t have one, read my research on the best swimming pool test kits.

Step 1: Collect a Sample

Dip the tester in the pool to collect a pool water sample from a few inches below the surface (elbow deep is generally a good guideline). This ensures that you’re testing the water representative of the overall pool, rendering a more accurate test result. Ensure that the vial is filled to the “fill” line.

Step 2: Add Reagent

Add the required amount of CYA reagent to the water sample.

Step 3: Mix it Up

Put the cap on the tester and mix the water sample and reagent thoroughly for the amount of time required by the manufacturer.

Step 4: Check for Results

After mixing the solution, wait a few seconds for the color to develop. The color will change based on the amount of cyanuric acid present in the water. Hold the test tube up to the color chart in the test kit to get an accurate reading. If you’d like, record the result to keep track of the CYA levels over time to help identify any patterns.

Taylor High Range Swimming Pool Test Kit

This expansive test kit includes nine tests for most pool chemical measurements you need.

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Step-by-Step Guide: How to Test the Cyanuric Acid Level In Your Pool Using A Test Strip

Here’s a simple step-by-step on testing cyanuric acid levels in a pool using a test strip.

Step 1: Dip

Dip your test strip in elbow-deep water for a couple of seconds. Make sure to only hold onto the white part of the test strip. Do not make any direct skin contact with the colored part of the strip, or the test will be rendered inaccurate.

Step 2: Wait

Extract the strip from the water and hold onto it for around 10 seconds. If you don’t see any colors changing as the strip reacts to the chemicals in the water, you may need to fish out a new strip and try again.

Step 3: Check

After the colors have appeared, the final step is to compare the colors on the strip to the color chart provided on the test strip kit. Hold your test strip against the chart to determine your CYA levels. Make sure to compare the test strip to the color chart as soon as possible, as waiting longer than a minute may cause inaccurate readings. Throw away the used test strip afterward!

AquaChek 7-Way Pool and Spa Test Strips

These are great test strips that test for seven important levels in just a few seconds.

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How to Raise or Lower Cyanuric Acid Levels

If you have determined that you have too little or too much cyanuric acid in your pool, it’s time to balance the levels out.

How to Raise Cyanuric Acid Levels

There are two ways to raise cyanuric acid levels in your pool:

  1. Add more cyanuric acid: If you’re using a granular cyanuric acid, use a skimmer sock to disperse the chemical properly and put it in the skimmer or over the return jet. Alternatively, you can pre-mix it in a bucket and then pour it into the skimmer. If you’re using a liquid cyanuric acid, simply pour it into the skimmer. Make sure to add small amounts at a time; it’s much easier to raise CYA levels than to lower them.
  2. Use stabilized chlorine: Stabilized chlorine, like dichlor and trichlor, already have CYA. Balance your chlorine to get it to 1 to 3 ppm. By doing so, you will also be raising your CYA levels.

How To Lower Cyanuric Acid Levels

There are two methods for lowering cyanuric acid levels:

  1. Dilute the water: Use the partial drain-and-refill method to get your CYA levels back on track. The percentage of water you need to drain will be equal to the percentage of CYA you need to reduce.
  2. Use a cyanuric acid reducer: If you prefer not to drain your pool, a cyanuric acid reducer is a great alternative. To do so, first, make sure your pH and TA levels are balanced and ensure your chlorine levels are on the lower side. Then add the reducer around the perimeter of your pool and keep the pump running for 4 to 6 hours. Retest your CYA levels after 7 days.

If high cyanuric acid levels are a recurring issue, you could simply be using too much of it. One of the major causes of high CYA levels is stabilized chlorine. For example, a pound of trichlor in a 10,000-gallon pool can raise your CYA levels by 6 ppm. Make sure you are not accidentally double-dosing your pool with additional CYA if it is already included in the chlorine you are using!

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If you have any questions about cyanuric acid or queries concerning your pool chemistry, shoot me a message! I’ll be happy to help out.

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