Additional solutes are present in some cases, such as generic multivalent ions, denoted as M 2+ , X 2 -, or a small diprotic weak acid (succinic acid) in all of its ionization forms H 2 SuA, HSuA -, SuA 2 -. All solutes are being exchanged with the supernatant as described in Sec. 2.2, hence their numbers fluctuate. They are all represented as point particles with λ = 0, an effective diameter σ i = 0.355 nm instead σ mon and the respective charge number z i , as depicted in Figure and listed in Tab. S2 in the ESI.