Abstract: The disclosure relates to a separation process. An aerated inlet mixture of fluid and solids is fed to a flotation separation vessel and is separated into an upper float layer and a lower clarified layer. The upper float layer is withdrawn from the vessel when the height of the upper float layer exceeds the height of an overflow conduit and forms a concentrated solids effluent The lower clarified layer is withdrawn from the separation vessel as a clarified fluid effluent. The separation process is performed continuously using a control process that maintains a relatively stable distribution between the lower clarified layer and the upper float layer. The control process is a closed loop process that monitors the instantaneous height of the vessel contents and computes an error function based on the instantaneous height and a set-point height The error function is used to periodically adjust the outlet flowrate of the clarified fluid effluent. The resulting process has improved stability (e.g.