Pool & Spa Pool Cyanuric Acid Calculator
Created by: Emma Collins
Last updated:
Estimate stabilizer additions to reach target CYA and calculate dilution percentage if cyanuric acid is above the desired range.
Pool & Spa Pool Cyanuric Acid Calculator
PoolEstimate stabilizer dosing and high-CYA dilution guidance
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What is a Pool & Spa Cyanuric Acid Calculator?
A Pool & Spa Cyanuric Acid Calculator estimates stabilizer additions for target CYA and provides dilution guidance when CYA is too high.
Use this with the Pool Chlorine Calculator and Pool Volume Calculator for UV and sanitizer planning.
CYA Formulas
Stabilizer (lb) = (CYA Increase ÷ 10) × 1.3 × (Pool Gallons ÷ 10,000) × (100 ÷ Purity%) If CYA is above target: Dilution % = ((Current CYA - Target CYA) ÷ Current CYA) × 100
How to Calculate Stabilizer: Example Calculations
Pool 20,000 gal, CYA from 20 to 50 (+30): Stabilizer = (30 ÷ 10) × 1.3 × 2 = 7.8 lb
Current CYA 100, target 60: Dilution % = (100 - 60) ÷ 100 = 40%
Common Applications
- Outdoor chlorine UV protection planning.
- Post-rain and refill stabilizer corrections.
- Service-route CYA standardization by pool size.
- High-CYA dilution planning workflows.
Tips for Accurate Results
- Dissolve stabilizer per label guidance and circulate fully.
- Avoid large single additions without retesting.
- Coordinate CYA targets with chlorine management strategy.
- Use reliable CYA testing methods and consistent sampling.
Frequently Asked Questions
What is cyanuric acid in a pool?
Cyanuric acid (CYA), also called stabilizer or conditioner, protects free chlorine from rapid UV degradation in outdoor pools. Appropriate CYA levels help maintain sanitizer persistence during sunlight exposure. Targets vary by sanitizer type and local operating strategy.
How much stabilizer raises CYA?
A common estimate is about 1.3 lb of stabilizer per 10,000 gallons to raise CYA by roughly 10 ppm, adjusted for product purity. Because CYA dissolves gradually, additions should be staged and retested after full mixing before extra product is added.
Can I lower CYA with chemicals?
In most practical maintenance workflows, high CYA is reduced by dilution rather than direct chemical removal. Partial drain-and-refill with lower-CYA water is commonly used to return to target range. Plan dilution carefully to protect equipment and local compliance requirements.
What happens if CYA is too high?
Excessive CYA can reduce active chlorine effectiveness and complicate sanitation control, often increasing required free chlorine setpoints. Keeping CYA in a suitable range supports more predictable chlorine behavior and easier routine maintenance.
Should CYA be adjusted with chlorine planning?
Yes. CYA and chlorine targets are linked in outdoor pools. Stabilizer corrections should be paired with sanitizer planning so free chlorine goals remain appropriate for your operating range and water conditions.
Sources and References
- PHTA chemistry recommendations for outdoor chlorinated pools.
- Manufacturer cyanuric acid dosing labels.
- CDC MAHC chemistry management guidance.