Detachment of polystyrene Infer colloids was studied in a model porous media system comprised of a packed column of glass beads. The polystyrene colloids were attached and subsequently detached from the glass bends by varying solution pH and ionic strength. It was found that classical-DLVO theory could not predict detaching conditions. Extended-DLVO theory was used to determine the median detaching pH for deionized water; and solutions of 0.01 and 0.1 M NaCl. Although both the colloids and porous media were macroscopically, homogeneous, detachment was observed at a variety of pH values. The pH distribution of detachment and the energy distribution of the interaction between die polystyrene latex colloids and the glass bends followed gamma distributions. This work has provided a technique to quantitatively pr edict the aqueous chemistry changes that induce colloid detachment in porous media.