In an apparatus containing rotating filter media that removes solids from a fluid stream, the invention provides devices and methods for improved cleaning of the filter media. Solids trapped on the filter media are removed by the application of a suction pressure that draws the filter media into contact with a backwash shoe. The backwash shoe has one or more orifice slots in a radially tapered or oblique angular configuration or in a combination of radially tapered and oblique angular configurations. The orifice slot configuration creates an hydraulic condition where the unit of orifice area applied per unit filter area has a generally uniform ratio across the rotating filter media. This configuration equalizes the distribution of the backwash flow over the filter area, thereby maintaining the filter media in a more uniformly clean and effective filtering condition.