Abstract: Improved skimmer apparatus for use in dissolved air floatation basins employed in water purification and waste water treatment plants is provided. The invention includes centrally positioned, longitudinal guide rails affixed to the basin and two or more interconnected reciprocating carriages, each carriage having a skimmer blade affixed thereto, the carriages being moveably mounted on the rails. At the effluent end of the basin is an upwardly shaped ramp, and the carriage nearest in proximity to the ramp has a ramp profile duplicating mechanism pivotally mounted to it.