A method for facilitating removal of mercury from a primary fluid stream of interest which is contaminated with organically-bound, elemental, and ionic mercury species. The stream is analyzed to establish the relative content of the organically-bound, elemental, and ionic mercury species present therein by forming a diverted side stream from the primary stream, and passing the side stream successively through three in series filter stages, the first captures organically bound mercury, the second captures elemental mercury, and the third captures ionic mercury. The side stream flow through the filter stages is continued for a predetermined period, and upon conclusion of the period the quantity of mercury collected at each of the filtration stages is determined. This data is then utilized to determine the capacity of the three different filtration stages required to reduce the mercury content in the mam stream to a desired level.