What is cyanuric acid and why does it matter?
Cyanuric acid, also called stabilizer or conditioner, protects chlorine from being destroyed by sunlight. Florida pools need it. Too much of it slows chlorine down until the pool grows algae despite testing fine, and the only reliable way to reduce it is to replace water.
Why Florida pools need it at all
Unstabilized chlorine in direct Space Coast sun burns off extremely quickly. Stabilizer holds chlorine in the water long enough to do its job through the day, which is why an unstabilized pool here can lose sanitizer faster than it can be added.
How it creeps up without anyone adding it
Chlorine tablets and stabilized shock contain cyanuric acid. Every tab adds a little, and it does not evaporate or break down — it only leaves with water. Year-round tab use is how most pools drift high.
The symptom people misread
A pool with very high stabilizer tests with chlorine present but behaves as if it has none: algae grows, water dulls, and adding more chlorine barely helps. Owners usually respond by adding more tabs, which makes it worse.
Bringing it down
- Partial drain and refill is the standard fix — replace water, dilute the level
- Switch to liquid chlorine or a salt system so it stops climbing again
- Recheck after the refill settles, because fill water changes hardness too
- Never drain a Florida pool fully without checking the water table first