Cyanuric Acid Hot Tub-Should Hot Tub Owners Avoid It?


So, you’ve got a hot tub, and you’re all about keeping that water sparkly clean and safe, right? I feel you. But here’s the thing: there’s a bit of a debate going on about something called cyanuric acid (CYA). Even if you do not use it directly, there are products designed for hot tubs that include CYA in their formulation. Now you may ask, should I be using cyanuric acid in the hot tub?

No, according to the CDC, you should avoid using cyanuric acid in hot tubs as the risks and issues outweigh the benefits it provides. Using it may cause skin irritation, and itching, increase germs by reducing the effectiveness of chlorine, and may require frequent water draining and filling. So, a cyanuric acid hot tub is a big no. Don’t stress it, I will give you some alternatives to cyanuric acid for your hot tubs and more in today’s article.

Cyanuric Acid: What Is It?

Cyanuric Acid: What Is It?

Let me give you a little briefing on what is cyanuric acid (CYA) first then I will elaborate on how it made its way into hot tub care.

Cyanuric acid is a stabilizer for chlorine. It’s been a big deal in swimming pools since the ’50s because it helps keep chlorine from getting zapped by sunlight. Pretty neat, huh? But when it comes to hot tubs, the story changes a bit.

From Pools to Hot Tubs: A Surprising Shift

Here’s where it gets interesting. Hot tubs aren’t just oversized bathtubs; they’re a whole different ball game. They’re usually covered and don’t get as much sun, so the whole UV protection thing with CYA? Not really a biggie. But, guess what? CYA still made its way into hot tub care, mostly through products like dichlor. It’s like using sunscreen at night – not exactly necessary.

Cyanuric Acid In Hot Tub: Why Many Hot Tub Owners Use It

Let me narrow down on reasons why hot tub owners use cyanuric acid in their hot tubs.

  • Prevents Chlorine Loss from Sunlight: First off, cyanuric acid is like the superhero bodyguard for chlorine. It wraps around chlorine molecules, shielding them from the harsh UV rays of the sun. This means your chlorine doesn’t just vanish into thin air – it sticks around, doing its job like a champ. So, you get to enjoy a sanitized hot tub without constantly adding more chlorine. Pretty neat, right?
  • Maintains Constant Chlorine Levels: Consistency is key, and cyanuric acid knows it. By stabilizing chlorine, it keeps the sanitizer level steady in your hot tub. Why does this matter? Well, consistent chlorine levels mean your hot tub is always ready for a dip, free from unwanted germs and bacteria. It’s like having a reliable friend who’s always there to keep things clean and safe.
  • Prevents Unexpected pH Changes: Here’s where cyanuric acid does a bit of behind-the-scenes magic. It’s not just about protecting chlorine; it also helps keep your hot tub’s water chemistry balanced. This means fewer wild swings in pH levels, making your soak time more comfortable and less of a guessing game. Think of it as the zen master of your hot tub, keeping everything calm and balanced.
  • Reduces Frequency of Chemical Adjustments: Let’s face it, fiddling with chemicals isn’t anyone’s idea of fun. Thankfully, cyanuric acid cuts down on this chore. Its stabilizing powers mean you’re not constantly tweaking and adjusting chemicals. This leads to a more straightforward, hassle-free hot tub experience. More time enjoying, less time tinkering – that’s the goal!
  • Minimizes Chlorine Demand: Cyanuric acid is all about efficiency. It helps your chlorine last longer, so you’re not constantly pouring more in. This means you get the most bang for your buck with your sanitizing chemicals. It’s like having a fuel-efficient car – you go longer between fill-ups.
  • Supports Long-Term Cost Savings: Last but not least, let’s talk about the moolah. Cyanuric acid helps your chlorine last longer, which means less money spent on chemicals. Over time, this adds up to some sweet savings. It’s like finding a little extra cash in your pocket – always a welcome surprise!

Why It Is Not A Good Idea To Use Cyanuric Acid In Hot Tubs?

Why It Is Not A Good Idea To Use Cyanuric Acid In Hot Tubs?

I have listed a few reasons why you should avoid using cyanuric acid in your hot tub.

Unsafe Chlorine Levels

Ever heard of “chlorine lock”? It’s like putting too much sugar in your coffee – there’s no going back. Overdoing it with CYA can lead to a buildup that messes with your chlorine levels, making it less effective. That is not exactly what you want when you’re trying to keep those germs at bay.

The Itch Factor: Skin Irritation Risks

Hot tub itch – sounds fun, right? Not so much. Too much CYA can make your skin go all red and itchy. Imagine trying to relax in your hot tub and ending up feeling like you’ve been attacked by a swarm of invisible mosquitoes. No thanks!

The Algae Paradox: Growth Concerns

Here’s a weird twist: CYA is supposed to stop algae from crashing your hot tub party, but if you go overboard, it can actually roll out the red carpet for them. It’s all about balance, folks.

Tabe: Impact of CYA on Kill Times

CYA Level (ppm)Kill Time for Pseudomonas Aeruginosa
020 seconds
501 minute 30 seconds
100Nearly 2 minutes

Reduced Effectiveness

Think of CYA as that friend who’s great in small doses but a bit of a downer in large ones. When there’s too much of it, chlorine just can’t seem to get off the couch and do its job. The result? Not-so-clean water. Consider a hot tub used twice a week by two people. This usage can lead to a weekly increase of 12.6 ppm in CYA, making chlorine less effective over time.

Potential Impact on Water Balance

Getting the water balance just right in your hot tub can be tricky. Too much CYA can throw everything off, like pH levels and alkalinity. It’s like trying to walk a tightrope while juggling – possible, but challenging.

Difficulty in Lowering Cyanuric Acid Levels

So, you’ve got too much CYA. Now what? Diluting it with fresh water might work, but it’s like trying to empty a swimming pool with a teaspoon. A lot of effort for not much reward.

Impact on Indoor Hot Tubs: Do You Even Need It?

If your hot tub is indoors, away from the sun’s UV rays, the whole CYA thing might be overkill. It’s like wearing a raincoat indoors – why bother?

Potential Corrosion Issues

Too much CYA can be tough on your hot tub, leading to corrosion. It’s like that friend who always borrows your stuff and never returns it in one piece.

Health Concerns

For folks with sensitivities or allergies, CYA can be a real party pooper. It’s all about keeping things balanced for everyone to enjoy a dip without any drama.

Official Stance and Health Concerns

Even though many hot tub owners are using CYA, does not make it the right decision.

CDC and Health Department Warnings

The concerns regarding cyanuric acid in hot tubs are not just theoretical but are backed by official health organizations my friend:

  • CDC Recommendation: The Centers for Disease Control and Prevention (CDC) explicitly recommends against using cyanuric acid or chlorine products containing cyanuric acid in hot tubs. What a bummer! This recommendation stems from the increased kill times and reduced effectiveness of chlorine in the presence of CYA in your hot tub.
  • Pennsylvania Department of Health Statement: In a similar vein, the Pennsylvania Department of Health highlighted that even moderate levels of cyanuric acid can extend the time it takes for chlorine to kill Pseudomonas aeruginosa by up to 100 times compared to hot tubs without cyanuric acid.

The Risks of Ignoring Guidelines

If you are one of those who hates guidelines then ignoring these guidelines and continuing to use CYA in hot tubs can lead to several risks:

  1. Health Risks: Extended kill times for bacteria mean a higher chance of skin irritations and infections for users. You don’t want that, right?
  2. Maintenance Challenges: High CYA levels can lead to cloudy water, bad odors, and skin irritations, making hot tub maintenance more difficult and less enjoyable for you.
  3. Case Study: A hot tub owner who used dichlor regularly experienced cloudy water and skin irritation. After testing, it was found that the CYA levels were excessively high, leading to ineffective chlorine sanitization.

With all the potential health issues and the hassle of keeping your tub clean, it might be time to look for other ways to keep your water sparkling.

The Dichlor Dilemma In Hot Tub Sanitization

Are you using dichlor like most hot tub owners in the USA? Then this portion is for you.

Dichlor: A Common Source of CYA

Dichlor (sodium dichloro-striazinetrione) is a popular chlorine product used in hot tubs, but unfortunately, it contributes significantly to CYA buildup:

  • Chemical Composition: Dichlor is about 50% CYA. This means that its regular use in hot tubs leads to a rapid increase in CYA levels. So, every time you’re aiming to clean up your tub, you’re also cranking up the CYA levels. Sneaky, huh?
  • Labeling and Misconceptions: Despite being labeled with its chemical name, many hot tub owners may not be aware of the cyanuric acid content in dichlor and its potential effects.

Rethinking Chlorine Use in Hot Tubs

The prevalent use of chlorine, particularly dichlor, in hot tubs calls for a reassessment, I have provided reasons as well:

  • Statistics: According to PK Data in the APSP 2018 Yearbook, 60% of all hot tubs are sanitized with chlorine, with dichlor being the most recommended type.
  • The Need for Change: Given the issues associated with CYA buildup, there’s a growing need to explore alternative sanitization methods that do not contribute to these problems.

How To Test For Cyanuric Acid Levels In Hot Tub Water?

How To Test For Cyanuric Acid Levels In Hot Tub Water?

In case you are not sure if your hot tub water has cyanuric acid or not you can test for cyanuric acid levels easily. You may use a liquid drop test kit or a test strip. Between these two methods, using the test strip method is much easier. I recommend using AquaChek 7-Way Pool and Spa Test Strips as it is one of the best and most reliable cyanuric acid test strips out there for hot tubs.

Step-By-Step Guide To Use AquaChek 7-Way Pool and Spa Test Strips

  1. Read the Instructions: Carefully read the instructions provided with the AquaChek test strips. Familiarize yourself with the specific steps for testing cyanuric acid.
  2. Dip the Test Strip: Submerge the AquaChek 7-Way Test Strip into the water sample up to the indicated line. Hold the strip in the water for the specified duration, usually a few seconds.
  3. Remove Excess Water: After the recommended submersion time, gently shake the test strip to remove excess water. Be cautious not to shake off the reagent pads at the end of the strip.
  4. Wait for Results: Allow the test strip to develop. The AquaChek 7-Way Test Strips typically provide results within seconds. Refer to the color chart on the test strip container for cyanuric acid levels.
  5. Match Colors: Compare the color of the cyanuric acid pad on the test strip to the corresponding color on the chart. The color match will indicate the concentration of cyanuric acid in parts per million (ppm).
  6. Record Results: Record the cyanuric acid level based on the color match. Note the numerical value or range associated with the color to accurately assess the concentration.
  7. Interpret Results: Compare the recorded cyanuric acid level to the recommended range for hot tubs, which is typically between 30 to 50 ppm. This will guide you in determining if any adjustments are needed.
  8. Take Corrective Action if Necessary: If the cyanuric acid levels are outside the recommended range, follow the appropriate corrective action. This may involve adding a cyanuric acid product or diluting the water with fresh water.
  9. Retest if Adjustments Are Made: After making adjustments, allow the water to circulate, and retest the cyanuric acid levels to ensure that the corrections have been effective.

5 Alternatives To Cyanuric Acid

Alternatives To Cyanuric Acid

So, you’re ready to break up with CYA? Great choice! Let’s explore some alternatives that’ll keep your hot tub party rolling without the CYA drama. Here’s the lowdown on some CYA-free options:

  1. FROG® @ease® with SmartChlor Technology: FROG® @ease® with SmartChlor Technology is indeed cyanuric acid-free. It’s designed to maintain a low level of chlorine without the need for cyanuric acid, making it a suitable alternative.
  2. Aquatic 2 Spa: Think of Aquatic 2 Spa as your hot tub’s eco-friendly helpers. They reduce the need for lots of chemicals and keep things clean.
  3. Natural Current Savior UV Sanitation: Natural Current Savior UV Sanitation uses UV energy to keep your water healthy.
  4. Oxy-Spa Chlorine-Free Oxidizing Shock: Oxy-Spa Chlorine-Free Oxidizing Shock can zap all the bacteria without needing the help of CYA.
  5. Leisure Time Mineral Purifier: Leisure Time Mineral Purifier uses natural minerals to help keep the water clean. It’s like giving your hot tub a bit of a nature boost.

Hot Tub Care: The Better Way

Now, no matter what you choose, here are some golden rules for hot tub care:

  • Test the Waters: Regularly check your hot tub’s pH and sanitizer levels. It’s like giving your tub a quick health check.
  • Keep It Clean: Regular cleaning is key. It’s not just about the water; give some love to the filters and the tub itself.
  • Balance Is Everything: Keeping your water chemistry balanced is like finding the perfect temperature for your hot tub – it just feels right.
  • Ask the Pros: If you’re ever in doubt, hit up a hot tub professional. They’re like the hot tub whisperers.

Final Thoughts

Alright, we’ve dived deep into the world of the “cyanuric acid hot tub” topic, and here’s the takeaway: CYA might not be the best plus-one for your hot tub party. It’s like that friend who starts out fun but ends up crashing on your couch way too long. We’ve seen how it can make chlorine slack off and give those pesky bacteria a free pass.

But hey, it’s not all doom and gloom. There are some awesome CYA-free options out there that can keep your hot tub sparkling without the side effects. Whether it’s ozone systems, UV sanitation, or mineral systems, you’ve got choices to keep your hot tub experience top-notch.


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I am Donald M. Beyer and I am backyard enthusiasts. I am a homeowner who has been doing DIY projects in and out of my house for many years. From simple backyard lunches to making an old-school pizza oven in my own backyard, I have a lot of experience in turning my backyard into my and my family’s personal playground.

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