Methods and electroplating systems for controlling plating electrolyte concentration on an electrochemical plating apparatus for substrates are disclosed. A method involves: (a) providing an electroplating solution to an electroplating system; (b) electroplating the metal onto the substrate while the substrate is held in a cathode chamber of an electroplating cell of electroplating system; (c) supplying the make-up solution to the electroplating system via a make-up solution inlet; and (d) supplying the secondary electroplating solution to the electroplating system via a secondary electroplating solution inlet. The secondary electroplating solution includes some or all components of the electroplating solution. At least one component of the secondary electroplating solution has a concentration that significantly deviates from its target concentration.