The anomalous behavior associated with polymer adsorption‐gel formation on a surface was investigated for the flow at low shear of aqueous Polyox coagulant and WSR‐301 solutions, containing 0–100 ppm of the polymer, in beds of monosized spheres. The flow measurements were conducted using stainless steel and Jaytron spheres and three sizes in the radius range 0.0796–0.2000 and 0.1187–0.1988 cm, respectively. The effective hydrodynamic thickness of the surface layer was evaluated from the negative effective velocity at the packing surface as an effective increase in the radius of the spheres. For the two Polyox homologs, the surface layer thickness increased with an increase in sphere radius and macromolecular size and exhibited a pseudo‐Langmuir‐type polymer concentration dependence, with a peak at the 30 ppm polymer concentration level. The present evaluations are in qualitative agreement with predictions based on the equation Δ=4AR2nfound for low shear tubular flow of the same solutions. The deviations from the equation are consistent with the expectation of physical entrapment in packed beds. The implications of the results in terms of resistance factors, residual resistance factors, and residual permeability reduction are presented.