Cyanuric Acid in Your Pool: Why It Matters and How to Fix It

Key Takeaways

• Cyanuric acid (CYA) acts like sunscreen for pool chlorine — without it, UV destroys half of unprotected chlorine in just 17 minutes.
• The Pool & Hot Tub Alliance ANSI standard sets the ideal CYA range at 30–50 ppm for traditional chlorine pools and 60–80 ppm for salt water pools.
• Cyanuric acid is not the same as muriatic acid. Muriatic acid lowers pH; CYA protects chlorine from sunlight.
• Low CYA means chlorine burns off fast, leading to algae and cloudy water. High CYA causes chlorine lock, where chlorine reads fine on tests but can’t effectively sanitize.
• The only reliable way to lower CYA is to drain and dilute — it does not evaporate or break down.
• Most pools drift into high CYA because Trichlor chlorine tablets are 50–55% cyanuric acid by weight.

Introduction

Clear pool water doesn’t always mean safe pool water. Many Houston pool service customers test chlorine, pH, and alkalinity faithfully every week … Read Full Post »