The PMT Acquisition Add-on module (PMTAcq) extends the IonWizard module into a full-featured ratiometric PMT acquisition system while allowing access to the analysis features of IonWizard during data collection. PMTAcq integrates seamlessly with the IonOptix PMT Sub-System to provide a coherent photometry solution. It provides integrated support for continuous ratiometric sampling using any IonOptix dual-excitation light source (HyperSwitch or µStep). PMTAcq displays raw and background-subtracted counts. For single wavelength dyes such as Fluo-3/4, PMTAcq also normalizes values to provide F0. For ratiometric dyes such as Fura-2 and Indo-1, PMTAcq performs real-time ratios as well as calibrated Ca2+.