Trouble with High Cyanuric Acid (or CYA)? Here’s How to Fix It (and Keep It That Way)
The following is general advice only. Requirements for individual pools and pool systems may vary.
Struggling to get your cyanuric acid (CYA) levels under control? If your CYA just keeps creeping up no matter what you do, the secret might lie in the type of chlorine you're using.
Let’s break down what’s really going on—and how to fix it.
Why High CYA Is a Problem
CYA acts as sunscreen for your chlorine. It helps protect your chlorine from breaking down under the sun’s UV rays, which sounds great—until you have too much of it.
When your CYA levels rise above 60-70 parts per million (PPM), your chlorine becomes too protected. That means it works slower, and in some cases, not effectively at all. This is particularly problematic during winter, when the sun’s UV rays do not evaporate chlorine much - if at all - depending on your climate.
The result?
✔️ Cloudy water
✔️ Algae growth
✔️ Frustration—even when your chlorine levels look "fine"
The Real Culprit: Stabilised Chlorine
If you’re using stabilised chlorine, this might be the reason your CYA keeps going up. This is because stabilised chlorine contains CYA.
Every time you add a stabilised chlorine, you're adding more CYA. Over time, it builds up—especially since CYA doesn’t break down or evaporate on its own, particularly in the colder months.
The Fast Fix: Switch to Liquid Chlorine
To stop the CYA climb, the first step is simple: Get your pool water tested.
If your CYA is within range, but your chlorine levels are low and not automated, stop using stabilised chlorine.
Switch to liquid chlorine, which contains no CYA. It’s unstabilised, so you can sanitise your pool without adding more stabiliser.
If your CYA is already high (about 70/80 PPM or more), liquid chlorine won’t be enough. You’ll need to drain and refill your pool to the required level to dilute the CYA to the required range (around 30–70 PPM). If you need to add chlorine in the meantime, use liquid chlorine.
How to Make the Switch (Safely)
Here’s a simple step-by-step to make the change:
Stop using stabilised chlorine immediately.
Partially drain and refill your pool to bring CYA below 70 PPM (ideal: 30–70 PPM).
If additional chlorine is quired, use liquid chlorine: Add as required.
Test your water 20 minutes after adding, then again the next day.
Maintain daily testing for a week, adjusting chlorine as needed to stay around 3 PPM.
Pro tip: In hot or sunny conditions, you might need to dose more often—liquid chlorine burns off faster without CYA, so consistent testing is key.
When (and How) to Return to Stabilised Chlorine
Once your CYA is back in the safe zone (around 30–70 PPM), you can start using stabilised chlorine again. Many pool owners find success by rotating between stabilised chlorine and liquid chlorine to maintain balance and prevent CYA overload. The balance depends a lot on your local climate.
Need help calculating how much liquid chlorine to add or how much water to drain? Drop by the store or give us a call—we're here to help you keep your pool sparkling and stress-free.
Final Thoughts
High CYA levels don’t necessarily mean you have to drain your whole pool or fight algae all season. While some draining may be necessary depending on your CYA levels, with a temporary switch to liquid chlorine and a little patience, you may be able to reset your water chemistry and get things back on track.
If your CYA levels are too high and won’t budge, contact us today or visit us in-store (2/439 Gympie Road) for expert advice.
📞📲 1300 447 665
🌐 www.waterpropools.com.au
🌐 info@waterpropools.com.au