Can you use cyanuric acid in hot tubs?

If you own a swimming pool, swim spa, or hot tub, you might have seen discussions about adding cyanuric acid (also known as CYA) to your pool. This chemical has many useful effects when it comes to protecting your water, but it also comes with controversial side effects – so should we be adding it to our hot tubs, or avoiding it?

Our guide will explain all you need to know about CYA and how to maintain a healthy amount of it in your hot tub. We’ll go into some of the pros and cons of cyanuric acid and explain the general importance of adding chemicals like this to your water.

What is Cyanuric Acid?

Cyanuric acid is a chemical compound made up of carbon and nitrogen and is often sold in the spa/pool industry as “pool conditioner” or “pool stabiliser”. Pool owners typically use CYA to protect the chlorine levels in their water, as the sun’s UV rays degrade chlorine sanitiser over time. But cyanuric acid protects it from sunlight, allowing outdoor pools to stay clean for longer with less maintenance.

If you add chlorine to your hot tub using granules, powder, or tablets, then you’ll likely be adding a small amount of CYA to your water with each top-up. Cyanuric acid also isn’t necessary in hot tubs that use bromine, so only chlorine users need to be conscious of their CYA levels.

Why is cyanuric acid controversial in hot tubs?

Cyanuric acid is important in outdoor pools because of how exposed they are to sunlight, but more often than not, your hot tub won’t be as open as a swimming pool. With indoor spas, tub covers, and more, sunlight will affect a hot tub much less than larger bodies of water.

Too much CYA in a hot tub, however, can cause your chlorine to be less effective at sanitising your water – this is known as “chlorine lock”. It’s important to monitor your levels to make sure you don’t reach this point, but it can be tough when you’re adding small amounts to the tub daily. Your hot tub could also be damaged by the wrong amount of pool stabiliser, which creates limescale that can erode your components over time.

There are also health issues raised by cyanuric acid, due to certain waterborne diseases being able to live longer in water containing this chemical. For example, the bacteria associated with hot tub rash can live for up to four times as long in water with high CYA levels, so bathing when levels are out of balance isn’t recommended.

What’s a safe level of cyanuric acid in my hot tub?

Despite its downsides, it’s hard to avoid having some CYA in your hot tub, and it’s safe when kept to a reasonable amount. Getting the right chemicals for your hot tub as a beginner can be intimidating, but it’s important to make sure the levels in your tub aren’t too high or low.

Ideally, your cyanuric acid levels should lie between 30 and 50 ppm (parts per million) to reap the benefits without risking permanent damage. Your CYA levels can fluctuate due to how often you’ll be adding more to your water, so make sure to take regular note of them and adjust for any errors.

How can I lower cyanuric acid levels in a hot tub?

If you’ve found out that your hot tub water contains too much cyanuric acid, it’s important to return your levels to the recommended range as soon as possible. You shouldn’t use a hot tub without adding chemicals, but here are a few ways you can reduce the amounts of CYA while sticking to your usual maintenance routine:

• Diluting your water – By draining some of the water from your hot tub and replacing it with fresh water, you can adjust your CYA levels cheaply and easily.
• Avoiding stabilised chlorine in your hot tub chemicals – While cyanuric acid is common in many hot tub chemicals, there are alternatives available that won’t raise your levels. Consider swapping chlorine for bromine when looking after your tub, or search the market for chlorine products that aren’t stabilised.
• Use a product that reduces CYA – Some chemicals counteract the stabiliser in chlorine products by breaking down molecules of CYA. If spending extra money on your upkeep isn’t an issue for you, this is one of the fastest ways to change your cyanuric acid measurements in a hot tub.

If you’re looking to shock your hot tub, you needn’t worry about cyanuric acid levels, as most shock products are stabiliser-free.

What are the pros and cons of cyanuric acid?

There’s plenty of debate among hot tub owners as to whether cyanuric acid is a useful chemical, or whether the disadvantages outweigh the advantages. It’s a matter of personal preference, but it’s worth remembering key points from both sides of the argument.

The pros:

CYA has the following advantages:

• It protects the chlorine in your water from degradation by UV rays.
• It makes your chlorine last longer, leading to less frequent maintenance.
• It works especially well in outdoor hot tubs or uncovered models.

The cons

CYA has the following disadvantages:

• Maintaining levels can be difficult with frequent additions.
• There’s a risk of health issues and hot tub damage when too much CYA is present in water.
• It makes chlorine less effective over time if allowed to accumulate.
• It has no direct sanitation benefits – CYA makes other sanitisers work more effectively instead of cleaning your water itself.

Learn more about looking after your hot tub with Platinum Spas

It’s tough to avoid adding cyanuric acid to your hot tub if you’re using the most common brands of chemicals, but it’s important to regulate the levels in your water. Frequent maintenance and check-ups can improve your hot tub’s health, prevent any problems before they occur, and keep your hydrotherapy sessions safe.

If you’re still looking for assistance, consider reading our other guides covering all you need to get the most out of your hot tub. We have articles showing you how to keep track of other important levels, such as balancing your hot tub’s pH or lowering its total alkalinity. Alternatively, you can get in touch with one of our Platinum Spas experts for curated advice on hot tub care.

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Jamie Smith

General Sales Manager at Superior Wellness

Jamie Smith is the general sales manager at Platinum Spas, and has years of professional expertise in the hot tub industry. From Business Development to Sales, Jamie has helped grow our business into a global powerhouse, working with our partners and developing our offering as we strive to be market leaders.

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