We determined how the model parameters affect the partition coefficients and shape of the phase diagram, particularly the region of phase coexistence. We showed that an increase in monomer size or a decrease in charge density both shrink the coexistence region whereas a decrease in permittivity of the PEC phase or a decrease in solvent quality, quantified by the second virial coefficient B 2 , both expand the coexistence region. Simultaneously, charge density and solvent quality have only negligible impact on the partition coefficients of small ions whereas the monomer size and permittivity of the PEC phase significantly affect the partition coefficients to such an extent that variation of these parameters may even switch the preferential accumulation of the ions from supernatant to the PEC phase. Thus, it should be always possible to tune the simulation model in order to match a specific set of experimental results. Additionally, various combinations of these parameters can lead to nearly identical phase diagrams, producing a good match with the experiment. Therefore, even a quantitative agreement between simulations and experiments does not automatically imply that the model parameters have been chosen correctly. Nonetheless, the generic patterns in the partitioning of multivalent ions, described above, may be quantitatively but not qualitatively affected by small changes in parameters of the model. where we see