A substrate ion exchange system, along with methods of maintain such a system, is provided that includes a substrate having an outer region containing a plurality of substrate metal ions, an ion exchange bath that includes a plurality of first metal ions at a first metal ion concentration and a plurality of second metal ions at a second metal ion concentration, and a vessel for containing the ion exchange bath and the substrate. The ion exchange system also includes a temperature sensor coupled to the vessel, and a processor configured to receive a vessel temperature from the sensor and to evaluate the first metal ion concentration based at least in part on a first metal ion consumption rate relationship and the vessel temperature. Further, the first metal ion consumption rate relationship is predetermined.