Finally, a long-hold polarization test enabled in situ acclimation for each Rext after long-term stability was reached. This method maintained ΔĪOS=0 and improved both Pmax and Īmax beyond those values obtained using the standard polarization test before the MFC overshoot began. By combining the in situ acclimation during a long-hold polarization test with an increased flow rate, Pmax and Īmax were further improved. We note that in the absence of any acclimation, the performance returned to the previously measured non-acclimated post-erosion levels.