pDADMAC pretreatment of mammalian cell culture, coupled with Clarisolve® depth filters, provides for an effective pretreatment method by shifting the particle size distribution towards larger particles which can then be ‘matched’ to a graded depth filter designed for higher solids loading. Flexibility in filtration performance around pDADMAC dosing, flux rates, mixing hold times, and the variability in cell culture harvests provides for a robust clarification platform. Additionally, utilizing Clarisolve® filters for direct harvests, allows for a more compressed clarification train, through the compression of primary and secondary filtration, and thus a smaller footprint.