Liquid fluidized beds of angular particles exhibit channelling. Unsteady-state tracer injection experiments do not allow accurate detection of channelling. Two new, more sensitive, techniques to estimate channelling were developed : local conductivity measurements within the bed and cross-sectional average conductivity measurements from steady-state liquid tracer injections into the bed. The complete fluidization velocity can be estimated from local conductivity measurements and from the fractal dimension of unsteady-state tracer injections both into the bed and upstream of it. Jet mixing is a practical and effective method for reducing channelling in liquid fluidized beds without increasing particle entrainment.