The Pool Guy Talks Pool Chemistry

What is Cyanuric Acid (CYA)?

Cyanuric Acid—often labeled “Conditioner” or “Stabilizer”—protects chlorine from being destroyed by sunlight. Without it, UV rays rapidly burn off free chlorine, forcing constant re-dosing and leaving water vulnerable to algae and pathogens on bright summer days.

Why CYA matters

  • Protects sanitizer: CYA binds with chlorine to shield it from UV, helping your free chlorine last longer outdoors.
  • Supports consistent water quality: With the right stabilizer level, you can maintain safer, steadier chlorine residuals.
  • Prevents chemical waste: Proper stabilization means fewer large swings and less wasted chlorine.

The ideal range (and our recommendation)

For most outdoor residential pools, the recommended range is 30–80 ppm. At Dynamic Pools and Spas, we generally target ~40 ppm for balanced protection and control in typical backyard pools. Your ideal set point can vary based on pool type, sun exposure, bather load, and equipment—so test and adjust with intent.

Pro tip: After any drain/clean/refill, tap water will contain almost no CYA. Plan to add stabilizer to bring levels into range.

How CYA gets into your pool

Many popular chlorine products—trichlor tablets and dichlor granular—are “stabilized,” meaning they already contain CYA and will slowly raise the level over time. That’s why a pool that uses stabilized chlorine season after season can see CYA creep upward.

When to add CYA

  • After refilling with fresh tap water
  • When testing shows low CYA (below ~30 ppm)
  • When sunlight is rapidly consuming chlorine despite proper dosing

If you’re uncertain, we can test your water and advise on dosing.

Testing CYA (and how often)

You can use:

  • Drop-based test kits that include a CYA test
  • Professional testing (recommended if results are inconsistent or you’re troubleshooting)

How often: About once a month during the season, or any time you struggle to maintain chlorine or notice unusual readings.

How to add CYA (do this right)

Always read and follow the product label. Depending on the brand, directions may call for:

  • Pre-dissolving in a bucket and pouring around the pool perimeter, or
  • Broadcasting directly into the pool water and brushing to help it dissolve

Important: We do not recommend pouring chemicals directly into the skimmer unless the manufacturer specifically instructs it for your system. Improper addition can damage equipment or trap undissolved product in plumbing.

“My CYA is too high—now what?”

There’s no practical chemical reducer for CYA in standard pool care. If your level climbs well beyond the ideal range, the effective remedy is:

  • Partial drain and refill, or
  • Complete drain and refill in more severe cases (performed safely to protect the pool structure)

Because stabilized chlorine adds small amounts of CYA every time you dose, long-term use without periodic dilution can push levels higher than desired.

Backwashing after adding CYA

After dosing, avoid backwashing for 48–72 hours (per most manufacturer labels). Backwashing too soon can remove newly added stabilizer before it fully dissolves and distributes.

Signs you should check your CYA

  • You’re losing chlorine quickly during sunny weather
  • You’ve recently drained/refilled or switched sanitizers
  • Your readings are inconsistent week to week
  • You’ve used stabilized chlorine exclusively for an extended period

Quick reference: CYA do’s and don’ts

Do

  • Test monthly in-season
  • Dose according to label directions
  • Re-test 5–7 days after adding to verify results
  • Keep records of your levels and products used

Don’t

  • Add stabilizer blindly without testing
  • Backwash within 48–72 hours after dosing
  • Pour chemicals into the skimmer unless the label clearly instructs it

FAQs

What number should I aim for?
Most backyard outdoor pools do well between 30–80 ppm; we typically recommend around 40 ppm for many southeast Michigan pools. Unique conditions may call for adjustments.

If my CYA is low but chlorine still disappears, what else should I check?
Confirm pH, free chlorine, and combined chlorine (chloramines), and review sunlight exposure, bather load, and filtration run time.

Can I switch products to control CYA?
Yes. If levels are climbing, consider non-stabilized chlorine sources for a period (e.g., liquid sodium hypochlorite or calcium hypochlorite) and partially dilute the pool to bring CYA back into range.

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