CYA Pool Stabilizer Guide: Test & Manage Levels

🔬 Quick Reference

Ideal Range: 30-50 ppm (salt pools often 50-75 ppm)
Test Frequency: Monthly
Dosage: 1 lb per 10,000 gallons = ~12 ppm
Warning: Over 80 ppm significantly reduces chlorine effectiveness

Cyanuric Acid (CYA), commonly called "pool stabilizer" or "conditioner," is your chlorine's bodyguard against the sun. Without it, UV rays can destroy chlorine rapidly—often tens of percent per hour in strong sunlight.

How CYA Works

CYA forms weak chemical bonds with hypochlorous acid (active chlorine), creating "stabilized chlorine" that resists UV breakdown. This bonding is reversible—chlorine can still sanitize when needed, but stays protected when idle.

💡 Pro Tip: Think of CYA as sunscreen for your chlorine—essential protection that shouldn't be overdone.

Optimal CYA Levels

CYA Level	Status	Effect
Under 30 ppm	⚠️ Too Low	Rapid chlorine loss, higher chemical costs
30-50 ppm	✅ Ideal	Perfect UV protection, maximum chlorine effectiveness
50-80 ppm	⚠️ Acceptable	Good protection, but requires higher chlorine levels
Over 80 ppm	❌ Too High	Sanitization becomes difficult—must maintain much higher chlorine

🧂 Salt Pool Note: Salt chlorine generators often run effectively with higher CYA (50-75 ppm) since they produce chlorine continuously.

Testing CYA

Test monthly using a turbidity test kit specifically designed for cyanuric acid. Standard OTO and FAS-DPD test kits measure chlorine, not CYA.

🛒 Shop CYA Testing Supplies
• Pentair Cyanuric Acid Test Kit - Dedicated CYA turbidity testing
• Taylor 9-Way Professional Test Kit - Complete water analysis
• Taylor 6-Way Trouble-Shooter Kit - Multi-parameter testing

Managing CYA Levels

Raising CYA

Add granular cyanuric acid directly to your skimmer or broadcast across the surface.

📏 Dosage Calculator:
1 pound per 10,000 gallons raises CYA by ~12 ppm
Always pre-dissolve or add slowly to prevent staining. Adjust for actual pool volume and product purity.

🛒 Pool Stabilizer Products
Granular cyanuric acid available in multiple sizes. Professional-grade stabilizers for effective chlorine protection. Search for "stabilizer" or "conditioner" to browse current options.

Lowering CYA

There's no simple in-pool chemical that reliably lowers CYA. The dependable options are:

Partial water replacement: Drain 25-50% and refill with fresh water
Reverse osmosis treatment: Professional filtration service that preserves water but costs more than partial replacement
Complete water change: Most expensive but fastest for severe cases
Biological treatments: Some enzyme products exist, though results vary

🔧 Water Management Tools
Submersible pumps for water removal, hose attachments for efficient draining, and water testing meters to monitor progress during dilution.

CYA and Chlorine Relationship

As CYA rises, your target free chlorine must rise proportionally. A common guideline: maintain free chlorine at roughly 7.5% of your CYA level, with adjustments for temperature and bather load.

CYA Level	Minimum Chlorine	Warm/Sunny Target
30 ppm	2.0 ppm	2.5+ ppm
50 ppm	3.0 ppm	4.0+ ppm
80 ppm	5.5 ppm	6.5+ ppm

⚠️ Why Pools Struggle: High CYA explains why pools with "adequate" chlorine readings still develop algae problems. At 80+ ppm CYA, you need significantly higher chlorine levels to maintain effective sanitization.

Common CYA Sources

Trichlor tablets (3" pucks): Adds ~6 ppm CYA per 10 ppm chlorine
Dichlor shock: Adds ~9 ppm CYA per 10 ppm chlorine
Granular cyanuric acid: Direct stabilization without chlorine

🛒 Chlorine Products
Cal-hypo shock (no CYA added), liquid chlorine, and salt water chlorine generators. Balance your sanitization strategy to control CYA buildup.

🍂 Seasonal Strategy

Establish CYA levels early in the season. In colder climates, some owners reduce CYA in fall since UV protection isn't needed during winter, making spring startup easier.

Frequently Asked Questions

Can I swim immediately after adding CYA?

Yes, cyanuric acid is safe for swimming once fully dissolved. However, wait for proper circulation (4-6 hours) to ensure even distribution.

Why is my CYA reading higher after winter?

CYA doesn't evaporate or break down. If you added stabilized chlorine or shock during the season, CYA accumulated. Spring testing often reveals these accumulated high levels.

Can I use stabilizer in a salt water pool?

Absolutely. Salt chlorine generators produce unstabilized chlorine that needs UV protection just like liquid chlorine.

What's the fastest way to lower CYA?

Partial water replacement is most cost-effective. Drain 50% of your water to cut CYA levels in half. RO treatment preserves water but costs more than partial replacement.

🎯 Expert Maintenance Tips

Using trichlor/dichlor regularly? Test CYA monthly to prevent buildup
New pools: Stabilize to 30-40 ppm before starting regular chlorination
Salt water pools need CYA too—generators produce unstabilized chlorine
CYA doesn't expire or evaporate—it accumulates until physically removed
Keep detailed logs of CYA additions to predict when dilution is needed