Anne Gosselin will present several changes made to the control algorithms during Rio Tinto Aluminium latest increases of cell productivity to take care of the significant impact such amperage increase has on cell resistance behavior and general cell performance. As a matter of fact, lower anode cathode distance operation and/or anode size enlargement have led to a significant drop in bath volume and at the same time, more alumina must be dissolved in a context of higher current density: Alumina dissolution and dispersion through the cell became an issue and the level of instability has risen and along with increasing instability, mucky cells became more frequent. To face this new reality and bring back cell performance to its former level or even improve it, instability procedure has been modernized in order to discriminate high and low frequency instabilities. Alumina feeding procedure also needed to be more robust against instability and be independent from instability procedure. Results from implementation at Alma plant are presented.