As rapid advancements of novel redox flow battery (RFB) chemistries continue, increasing the performance of these electrolytes as they interact with the cell hardware remains a persistent challenge. Though chemical lifetime of aqueous organic RFBs is one figure of merit demanding attention, all RFB chemistries can benefit from a detailed understanding of mass transport and electrochemical activity within the stack components. In this study we use fluorescence microscopy to rapidly image fluid flow and electrochemical activity through a combination of tracer particles and redox-active soluble quinones. We use several techniques for mapping fluorescent tracer particle trajectories to evaluate fluid streamlines, local velocities and spatial heterogeneities. This information is then coupled with a spatial distribution of quinone fluorescence, which is used to determine local state of charge and rates of diffusion and advection. Consideration of regional mass transport is important for a comprehensive understanding of RFB performance; spatial heterogeneities in porous electrodes, which we observe over surprisingly large scales, can limit total flow battery performance due to higher mass transport overpotentials. Imaging experiments are designed in a bottom-up approach from a single wire to a full porous electrode, illuminating opportunities for rationally designed cell hardware to improve RFB performance for any chemistry.