The present work focuses on the experimental study of electrokinetic instabilities in non-dilute colloidal suspensions of nanometer scale polystyrene spheres. The addition of charged particles to a solution increases the conductivity of the solution due to the diffuse electrical double layer of ions surrounding each particle. Electrokinetic flows with conductivity gradients become unstable when the electroviscous stretching and folding of conductivity interfaces grow faster than the dissipative effects of molecular diffusion. In this work, a conductivity gradient is achieved at the intersection of a Y-shaped PDMS microchannel using pressure driven flows. Experimental scalar images, critical electric fields required for instability, and mean scalar energy perturbation fields over a wide range of applied D.C electric fields and conductivity ratios will be presented. Variation in the critical electric field and scalar perturbation values as a function of the pressure driven flow velocity will also be presented. These instabilities may be important in electrokinetic manipulation of non-dilute colloidal suspensions such as human blood, cells, material synthesis, or pharmaceutical development.