Hydraulic packed bed wash columns are continuous solid/liquid separators, which combine a virtually complete crystal/mother liquor separation with a highly efficient washing action at high throughput. A control strategy for these columns has been developed. Optimal set-points for the bed and the wash front height were determined. The shape of the wash front, dependent on its level and the geometry of the filters in the wash column, has been monitored and the results were correlated to flow simulations. Irreversible consolidation of the moving crystal bed unexpectedly occurred in the start-up phase of the experiments and this phenomenon is discussed here. Finally, design considerations on hydraulic wash columns are briefly outlined.