For each flowrate, the pH was electrochemically controlled by applying a potential bias of 1.65V to the protonator. This allowed the local pH to be set to ~5. This pH is lower than pH 6 the value where all free-chlorine is converted to hypochlorous acid; see bias, as shown previously in Figure (B) and (C). This suggests that there is great potential for future work on the coupling of these phenomena.