High levels of Cyanuric Acid (CYA) in pool water can cause issues. That's why Minimal CYA is Orenda's Fourth Pillar of Proactive Pool Care.
And yet, we encounter many people that are hesitant to drain—or even dilute—their pool to reduce CYA levels. Perhaps there are valid reasons—costs, structural risks, labor, environmental concerns—for not draining high CYA pool water. That being said, draining and/or diluting water is still the most economical way to lower CYA levels in a pool.