What is Cyanuric Acid (CYA)?

• CYA is a chlorine stabilizer that protects chlorine from being broken down by UV rays from the sun.
• It is commonly found in stabilized chlorine products like trichlor and dichlor.
• CYA is essential for outdoor pools but generally not needed in indoor pools where UV exposure is minimal.

How CYA Affects Your Pool

• Protects chlorine from sunlight – Without CYA, chlorine dissipates quickly when exposed to UV rays.
• Extends chlorine effectiveness – Helps maintain chlorine levels, reducing the need for frequent additions.
• High levels can reduce chlorine efficiency – Too much CYA can bind chlorine, making it less effective at killing bacteria and algae.
• CYA does not evaporate – Unlike chlorine, CYA stays in the water and builds up over time, requiring regular monitoring.

Ideal CYA Levels for Pools

• 30-50 ppm – Recommended for outdoor pools to ensure proper chlorine stabilization.
• 50-80 ppm – Sometimes used in pools with high chlorine demand, but risks reducing chlorine effectiveness.
• Over 100 ppm – Can cause problems by making chlorine less efficient, requiring higher chlorine levels to maintain sanitation.
• Over 150 and this is when you should start draining a little each week.
• 300 or higher is a full partial drain.
• Good Rule of thumb is the chlorine levels should be 7% of what the CYA level is. If CYA is 100, you need a 7ppm chlorine level for it to be effective.

How to Manage CYA Levels

• Regular water testing – Use a test kit or take a water sample to a professional pool store.
• Avoid overuse of stabilized chlorine – If CYA levels are rising, switch to liquid chlorine or non-stabilized shock. Good idea to switch to liquid in the winter and tabs in the summer!
• Dilution is the only way to lower high CYA – Partially drain and refill the pool with fresh water.If you have a sand filter, or a filter with a multiport valve, you can backwash the filter each week to help lower the water level.
• Monitor CYA in saltwater pools – Salt systems still require proper CYA levels for optimal performance. This is the only time you'll need to add CYA to the pool since salt water doesn't naturally have CYA built in the products like tabs.

Signs That CYA Levels Are Too High

• Chlorine is present but ineffective – Even with proper chlorine levels, algae and cloudy water persist.
• Increased chlorine demand – You need to add more chlorine than usual to maintain sanitation.
• Algae growth despite normal chlorine readings – High CYA can prevent chlorine from properly killing algae.

Conclusion

Cyanuric Acid is a crucial part of pool maintenance, helping to keep chlorine effective and ensuring a safe swimming environment. However, managing CYA levels is essential to prevent chlorine inefficiency and water quality issues. Regular testing and proper adjustments will help keep your pool water clear and balanced.

Need help balancing your pool’s CYA levels? PureBlu Pools can provide expert guidance and maintenance. Contact us today for a professional water analysis!