Stabiliser added to an outdoor swimming pool cyanuric acid bonds loosely to chlorine to minimise degradation by UV light.
While the addition of cyanuric acid reduces the degradation of free chlorine by UV light there is also a distinct disadvantage. Increasing concentrations of cyanuric acid reduces both the disinfection power and oxidation potential of free chlorine.
To offset the loss of disinfection power of free chlorine in stabilised outdoor pools the concentration of cyanurate must not exceed 50-60 mg/L (ppm). In any case not above 100 ppm.
Pool (Regular Dose): The proper use of stabiliser is to add cyanuric acid until the cyanuric acid reaches 50 mg/L (ppm).
At this concentration a non-cyanurate containing chlorine product such as sodium or calcium hypochlorite should be used until the cyanuric acid concentration drops to 25 ppm. Dosing cyanuric acid then be resumed until 50 mg/L is again reached.