Hi, Does anyone know why the decay of hypochlorite/free chlorine in pool water due to UV light might show a logarithmic decay (natural log) as opposed to an exponential one? I did a chemistry experiment with scaled up concentrations of chlorine and cyanuric acid (scaled up 25x). Even in the solution with no cyanuric acid it still shows logarithmic decay. Analysis was by titration. Excess potassium iodide and sulpuric acid was added and then it was titrated with sodium thiosulphate. I'm wondering because ALL secondary data I have found shows a logarithmic decay. With thanks, Jaamae.