With the goal of developing a technique to dynamically control the particle size of the crystals produced by a large crystallizer, we studied the relationship between the crystallization phenomena and the location of the feed in a classified bed crystallizer, through modeling and actual experiment. From the results of our investigations, we can conclude that a feed positioned inside the slurry phase of the crystallizer affects the crystallization phenomena. Positioning the feed within the slurry phase increases the crystal growth rate and the agglomeration of the seed crystals by increasing the degree of supersaturation at the inlet to the crystallizer. However, when the feed is positioned to the upper part of the slurry phase, the feed interferes with the agglomeration by reducing the concentration of the mother solution. We thus believe that we can dynamically change the particle size of the crystals that form in the crystallizer by moving the location of the feed to a point within the slurry phase.