What is the right Cyanuric Acid level in your spa pool or hot tub?

Want to know what Cyanuric Acid is and what levels of it is needed for your spa pool? This article covers what you need to know about the chemical.

What is the right Cyanuric Acid level in your spa pool or hot tub hero

What is Cyanuric Acid?

Cyanuric Acid is a product that stabilises chlorine sanitiser in your pool or spa. It's a type of chemical compound known as a triazine - and if you're into chemistry that means it contains 3 atoms of carbon and 3 atoms of nitrogen. It's also known as CYA and in the pool and spa industry can be called pool stabiliser or pool conditioner.

The purpose of cyanuric acid is to protect the active chlorine sanitiser in your spa pool and stop it from degrading in the UV rays of sunlight. It does this by stabilising the chlorine - it's like a sunblock for your spa sanitiser!

What is the right Cyanuric Acid level in my spa pool or hot tub?

The correct level of cyanuric acid in your spa pool should be between 30-50ppm (parts per million). To test your cyanuric acid levels, use a test strip that measures for cyanuric acid.

Do I need cyanuric acid in a spa or hot tub?

Yes! If you are using a chlorine sanitiser, you do need to use cyanuric acid to get help your chlorine work efficiently. Without cyanuric acid, your chlorine level can drop from the ideal range when exposed to the sun.

The most common chlorine sanitisers, dichlor and trichlor, already contain some cyanuric acid, so you don't need to add it separately. The level of cyanuric acid will build up with the continued use of either of these sanitisers.

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Why are the Cyanuric Acid levels high in my spa?

The first thing to determine is: how old is your spa water?

Is it a brand new spa? If so you are probably dosing with too much chlorine. You can’t ‘superdose’ with chlorine sanitiser like it was possible to do with other sanitising products like lithium which are no longer readily available. You should follow the manufacturer’s recommendations for the correct dosage for your spa - and start on the low end of the recommended range to avoid overdosing.

At the time of writing this guide, (November 2022) the recommended dosage for chlorine sanitiser is 6-10gms per 1000L of water daily.

Is it old water? If your spa water is more than 3 months old, you should dump at least half of your water and add clean water. This will reduce the level of cyanuric acid in your water and will enable your sanitiser to operate properly.

If you tried partially refilling with fresh water and things are still not as they should be, run a pipe-degreaser then completely drain your spa and refill with fresh water.

What are the symptoms of high cyanuric acid levels in my spa?

The symptoms of high cyanuric acid in a spa pool or swim spa show themselves in the form of smelly water and your sanitiser not working properly to kill bacteria. You might find yourself using more sanitiser to keep your water clear.

Other symptoms of high cyanuric acid levels can include itchy skin, red eyes and folliculitis.

Is cyanuric acid dangerous?

No, cyanuric acid is not dangerous at the correct levels. The ideal level of cyanuric acid is 30 to 50 ppm.

Is it safe to swim in a pool or spa with high cyanuric acid?

If the cyanuric acid level is too high, it can cause a high level of total dissolved solids (TDS), and cause chlorine to be inefficient. This means that the chlorine won't be doing it's job of sanitising your water properly - as a result there is a high risk of bacteria or viruses being present in the water.

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How do I measure cyanuric acid levels in my spa?

Use a test strip that includes cyanuric acid levels on it such as the BioGuard 6 in 1 test strips.

How do I get cyanuric acid down in a spa?

The best way to reduce the cyanuric acid in your spa is to partially drain your spa and refill with fresh water. If your cyanuric acid level is 5% too high, then you need to remove about 5% of the spa water and replace with fresh water.

If it is a while since you last changed your spa water, it is recommended to go ahead and completely change out your spa water. You should change your spa water every 3-6 months in a portable spa and 12-18 months in a swim spa, depending on usage.

Got more Questions?

Talk to us about your spa questions and we'll be happy to help!

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