5 Things to Know About Lowering Cyanuric Acid in Your Pool

Partial drain and refill is the only reliable method You must physically remove water from the pool and replace it with fresh water. No chemical additive actually destroys CYA despite what the bottle claims.

CYA does not go away on its own It doesn’t evaporate, doesn’t break down from sunlight, and won’t disappear over time. If your CYA is over 80–100 ppm (or 50 for saltwater pools), dilution is your only option.

Calculate how much water to drain with simple math If your CYA is 120 ppm and you want it at 40 ppm, you need to replace about two-thirds of the water (40/120 = 1/3 remaining). Drain 66%, refill, and retest.

Prevent high CYA by avoiding stabilized chlorine Stop using trichlor tablets or shock that contains CYA. Switch to liquid chlorine or cal-hypo for daily sanitation.

Keep CYA intentionally low from the start Add CYA only to a target of 30–50 ppm. This saves you from having to drain half the pool later.