How to Raise Cyanuric Acid Levels in a Pool

Learn to test, analyze, and adjust cyanuric acid levels to keep your pool healthy and clean

Co-authored by Jessica Gibson

Last Updated: September 30, 2024 Fact Checked

You're probably aware that your pool needs regular chlorine adjustments, but it's also important to balance cyanuric acid levels. Cyanuric acid is often sold as a conditioner or stabilizer because it prevents chlorine in the pool from weakening in the sunlight.^{[1]
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Research source} Use test kits or strips designed to measure cyanuric acid, so you can determine how much acid to add to your pool. To significantly raise levels, dissolve powdered cyanuric acid or add a liquid version. You can also add stabilized chlorine for regular maintenance.

Part 1

Part 1 of 2:

Testing Cyanuric Acid Levels

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Since the cyanuric acid needs to be balanced with the other chemicals in your pool, it's important to check this balance every week. For example, you might find that while cyanuric acid levels are fine, your chlorine level is off.^{[2]
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Retest the water after it's been diluted. If your outdoor pool doesn't have a cover and there's a lot of rainfall, the cyanuric acid may become diluted and ineffective. Remember to check the cyanuric acid levels if the pool's water becomes diluted.^{[3]
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- You can test the cyanuric acid levels as often as you like. If you believe the balance of your pool is off, test the cyanuric acid levels again even if it hasn't been a week since the last test.
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Use test strips. Buy strips that are chemically formulated to detect cyanuric acid. Keep in mind that many basic kits only test for chlorine and pH levels so you may need to buy a more advanced kit.^{[4]
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Research source} To use a strip, dip it in the water for about 30 seconds and compare the color on the strip to the color on the chart that came with the strips. This will tell you the cyanuric acid level in the water.
- Purchase test strips online or from your local pool supply store.
4
Consider using a liquid turbidity test kit. Some kits will come with a small container for gathering a water sample. Add the powdered solution and swirl the container so the water dissolves the solution. Wait 1 to 3 minutes and fill a sample cell with some untested pool water. Once the time is up, fill another sample cell with some of the tested pool water. You'll now be able to compare the results to an untested sample. Use the chart that came with the test kit to determine the cyanuric acid level in your pool.
- If you don't want to test the water yourself, fill a container with water and take it to your local pool supply store where they can test it for you. You'll need to gather about 2 tablespoons (30 ml).
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Determine if you need to add cyanuric acid to your pool. The cyanuric acid in your pool should be between 30 and 50 ppm, although some find it more effective closer to 80 ppm.^{[5]
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Research source} Keep in mind that the higher your cyanuric acid levels, the weaker your chlorine becomes.
- The World Health Organization recommends that cyanuric acid levels don't exceed 100 ppm.

Part 2

Part 2 of 2:

Adding Cyanuric Acid

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Buy powdered or liquid cyanuric acid from your local pool supply store. Keep in mind that if you buy it online, you may have to buy it in bulk.
If you need to adjust other chemicals in your pool water, start by adjusting the free available chlorine. Then add chemicals to adjust the total alkalinity and make corrections to pH before you add the cyanuric acid. Wait 3 hours and test the cyanuric acid level again.
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Calculate how much cyanuric acid to add. Follow the cyanuric acid manufacturer's instructions to determine how many pounds of cyanuric acid you need to add. You'll need to know how many gallons of water your pool holds as well as how many parts per million (ppm) of cyanuric acid you need to add.
- For example, if you need an extra 10 ppm of cyanuric acid in your 10,000 gallon (37850 l) pool, you'll need around 1 pound (1.86 kg) of acid.
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Dissolve powdered cyanuric acid in warm water. If you're using powdered cyanuric acid, fill a 5-gallon (18.9 l) bucket half full with warm water. Pour in the cyanuric acid and let it rest for at least 10 minutes so it dissolves. You can add it to the pool once the acid is dissolved.^{[6]
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- Remember to put on protective goggles and wear gloves when handling the cyanuric acid.
5
Pour the liquid or powdered cyanuric acid into the pool. Add the dissolved cyanuric acid or liquid cyanuric acid directly into the pool instead of into the filter tanks or skimmers. Once you've added the cyanuric acid, check the water's pH level and adjust it as necessary.
- Wait until no one is using the pool before you add the cyanuric acid. You can swim after 2 to 4 hours or once the pool has run a complete filter cycle.
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Use stabilized chlorine for a minor cyanuric acid increase. If your cyanuric acid level doesn't need a substantial increase (less than 10 ppm), buy stabilized chlorine. These tablets or sticks are chlorine combined with cyanuric acid. Follow the manufacturer's instructions to determine how many tablets or sticks to add directly to the pool.
- Stabilized chlorine is great for maintaining cyanuric acid levels in your pool because it doesn't dramatically change the acid level. If you’re unsure if the chlorine you’re using contains Cyanuric acid check the package. If the label mentions Trichlor or Dichlor it will add Cyanuric acid to your water. ^{[7]
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- Remember to check chlorine levels a few days after adding the stabilized chlorine.
Keep the pool pump running for at least 2 to 4 hours after you've added the cyanuric acid. The pump will agitate the water so the cyanuric acid is distributed throughout the pool.^{[8]
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Question

All readings are perfect, but the pool is very cloudy. What could it be?

Lee Ton

Community Answer

Cloudy water is frequently a result of algae in the early stages. Sounds like greenish water is next unless you get ahead of it with increased chlorine.

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I added stabilizer to my pool, and the entire pool went cloudy. Should I be worried? I added 4 lbs to a 12,500 gallon vinyl liner pool.

Lee Ton

Community Answer

4 pounds of CYA into a 12,500 gallon pool raised your CYA almost 40 ppm. This isn’t a worry, depending on your starting level. The cloudy water is likely a result of a lack of chlorine. It sounds like you’re in the early stages of an algae outbreak.

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How do I increase stabilizer?

Lee Ton

Community Answer

Stabilizer can be increased a few ways. First, liquid CYA exists, but is pricey. Second, granular CYA is out there. Last, stabilized chlorine such as dichlor and trichlor add CYA to the water. All the above methods will increase your stabilizer levels.

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If you have an indoor pool or hot tub, you won't need to use cyanuric acid. This is because sunlight won't destroy the chlorine in your pool as it does to outdoor pools or hot tubs.

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