Understanding Pool Stabiliser: Cyanuric Acid

Maintaining a sparkling clean and safe swimming pool involves a delicate balance of water chemistry. Among the various chemicals used, cyanuric acid (CYA) plays a crucial role.  What is another name for cyanuric acid? Often referred to as "pool stabilizer" or "chlorine conditioner," cyanuric acid is essential, particularly for outdoor pools, in ensuring chlorine's effectiveness. But what exactly is cyanuric acid, how does it work, and what are the important considerations for pool owners?

Related reading: Pool Water Testing 101: Essential Tips for Balanced and Safe Water

Table of Contents

• What is Cyanuric Acid in a Pool
  • How Does Cyanuric Acid Work
  • Is Cyanuric Acid Toxic to Humans?
• Pros and Cons of Cyanuric Acid
• Recommended levels for Cyanuric Acid
• How Do I Adjust the Cyanuric Acid in My Pool?
  • Increasing Cyanuric Acid (CYA) Levels
  • Decreasing Cyanuric Acid (CYA) Levels
• Key Takeaways

What is Cyanuric Acid in a Pool

Cyanuric acid is a white, odorless, crystalline powder that dissolves in water. It is specifically used in swimming pools and spas to stabilize chlorine and protect it from degradation caused by sunlight.

How Does Cyanuric Acid Work

CYA acts like sunscreen for chlorine. It forms a reversible bond, shielding chlorine from UV rays. This extends chlorine's life and maintains more consistent sanitation in sunny pools. It's a balance: CYA protects chlorine but also slightly reduces its immediate power.

Is Cyanuric Acid Toxic to Humans?

Cyanuric acid is not toxic to humans in typical pool concentrations and is safe for swimming. However, like all pool chemicals, it should be handled and stored responsibly, following safety guidelines. Direct contact with concentrated cyanuric acid powder can cause mild skin or eye irritation, and inhaling dust may irritate the respiratory system.

Pros and Cons of Cyanuric Acid

Benefits of Cyanuric Acid

• Cost-Effective: By stabilizing chlorine, cyanuric acid reduces the amount of chlorine needed over time, which can save money on pool chemicals.
• Consistent Chlorine Levels: Helps maintain a more stable chlorine level in outdoor pools, promoting better sanitation.

Drawbacks of Cyanuric Acid

• Reduced Chlorine Effectiveness: While cyanuric acid protects chlorine, it also reduces its ability to disinfect. As CYA levels rise, chlorine becomes less efficient at killing bacteria and algae.
• Over-Stabilization Risk: Cyanuric acid does not dissipate naturally; it accumulates in the pool water. If levels become too high, it can hinder chlorine’s effectiveness, leading to cloudy water and poor sanitation.
• Disinfection Impact: High levels of cyanuric acid can significantly reduce chlorine's ability to eliminate chlorine-resistant pathogens like Cryptosporidium.

Recommended levels for Cyanuric Acid

Maintaining cyanuric acid within the ideal range is crucial to balance chlorine stabilization with its sanitizing effectiveness.

• Ideal: 20-50 ppm (some experts suggest aiming for <30 ppm for better chlorine activity).
• Maximum: Should not exceed 100 ppm, with many guidelines recommending a max of 50 ppm or even 30 ppm for optimal disinfection.

How Do I Adjust the Cyanuric Acid in My Pool?

Cyanuric acid is useful for outdoor swimming pool maintenance, as it helps stabilize chlorine and reduce chlorine consumption. However, to ensure effective pool sanitation, proper levels must be maintained and over-stabilization avoided.

Increasing Cyanuric Acid (CYA) Levels

1. Test First: Use a pool test kit to check your CYA level. For most pools, it should be between 20 and 50 ppm.
2. Get CYA Increaser: Buy "CYA Increaser" or "Stabilizer" from a pool store. It looks like granules.
3. Figure Out How Much: The bag will tell you how much to use based on your pool size to raise the CYA. Start with the recommended amount.
4. Mix it in a Bucket: Fill a bucket with pool water. Slowly pour the CYA granules into the bucket and stir until they are dissolved. This takes a bit of stirring, so don't just dump the granules straight into your pool.
5. Pour into Pool: With your pool pump running, slowly pour the bucket of dissolved CYA into the skimmer or the pool's deep end.
6. Wait and Test Again: Let the pump run for a day. Wait a week before cleaning your filter. Then, test your CYA again to see if you added enough.

Decreasing Cyanuric Acid (CYA) Levels

1. Test First: Confirm your CYA is too high (over 50 ppm, ideally lower).
2. Drain Some Water: You need to drain some of your pool and refill with fresh water. A rough guide: For a little too much CYA, drain about 1/4 of your pool and refill. For a lot too much CYA, drain about 1/2 of your pool and refill. It's better to drain less and retest than drain too much!
3. Refill with Fresh Water: Use your garden hose to refill the pool.
4. Test and Rebalance: After refilling, test your pool water again for CYA and all other chemicals (pH, chlorine, alkalinity, etc.). You'll need to add chemicals to rebalance your water.

Key Takeaways

As a pool owner, here is what you need to know about cyanuric acid:

• Cyanuric acid (CYA) is "pool stabilizer" or "chlorine conditioner", making chlorine last longer.
• Maintain CYA levels in the 20-50 ppm range, ideally aiming lower (e.g., < 30 ppm).
• Regularly test CYA levels. To increase CYA, add a CYA increaser product. To decrease CYA, partially drain and refill your pool with fresh water.
• For indoor pools, CYA is generally unnecessary and often discouraged.

• Safety First: Handle pool chemicals carefully by wearing protection, following label instructions, never mixing them directly, and storing them safely out of reach of children and pets.