Cyanuric acid, or CYA, builds up in pools over time as a byproduct of stabilized chlorine products. In small amounts it protects chlorine from breaking down in sunlight, but once it climbs too high, chlorine stops working as well, even when levels look normal on a test strip. CYA reduction is the process of bringing that number back down.
Unlike calcium or dissolved solids, cyanuric acid can’t be removed with a filter or chemical additive — the standard fix has always been partial or full draining, since CYA only leaves the pool with the water it’s dissolved in. This is one of the more stubborn issues in pool chemistry, and it’s part of why CYA levels tend to creep upward year after year if nothing is done about it.
At No Drainer, reverse osmosis filtration offers a way to lower CYA without a full drain, since the membrane process separates it out along with other dissolved substances. Pools with chronically high cyanuric acid are one of the more common reasons owners look into this treatment specifically.
