Phytochlorin and its derivatives are used in photodynamic therapy to create singlet oxygen species that lyse cancer cells. Preparation of phytochlorin from plant extracts uses dead-end filtration after salt and solvent precipitation to recover viscous phytochlorin solids from mother liquor. We quantitate effects of particle size, pH, mixing, filter media, and batch-to-batch consistency on filtration rate and membrane capacity. Data show a characteristic particle settling time aids in filtering the sodium salt form of the phytochlorin compounds. Use of high energy mixing to prepare the phytochlorin precipitation increases filtration rate. Improvements to phytochlorin processing increased production rates of a photosensitive drug intermediate.