The real properties of the geometry of the capture region of the particles in the pores of the magnetic filters which are formed by magnetized ferromagnetic microparticles are investigated. The flow velocity profile of the liquid in this region is determined and the effect of the velocity profile to keep the particles in the pores is examined. The magnetic and the hydrodynamic powers have been expressed explicitly by considering, the pore geometry, magnetized property and the flow velocity. Obtained expression was explained on the V-m/V-f ratio, which is named as magnetic and flow velocities rate in filtering and separation processes. According to this expression, the volume and surface ratios of the particles which are accumulated in the particles capture region are taken into account. From theory and practice point of view, the derived expressions and results are put into a form to make easy to use for design, control and optimization of the filters.