4 Things to Know About Lowering Cyanuric Acid in a Pool

Draining and refilling is the only way to lower cyanuric acid (CYA). No chemical or additive can break down CYA once it stabilizes. You must physically remove over-stabilized water and replace it with fresh water.

Shock treatments, enzyme products, and “CYA reducers” do not work. The CYA molecule is stable and does not break down from chlorine or UV light. These products are snake oil for pools.

The amount to drain depends on your target CYA level. If CYA is 150 ppm and you want 50 ppm, replace about two-thirds of the water. Test after each drain and refill cycle to confirm the level.

Use a submersible pump or backwash into waste, but watch for restrictions. Check local water rules and your pool finish. Fiberglass and vinyl pools handle partial draining fine; plaster pools need caution with groundwater pressure.