An impeller blade formed of a central base portion having a center axis. At least a pair of impeller blades is extended outwardly from the central base portion, with each impeller blade further including an extension. A leading edge is formed on each of the impeller blades, with each leading edge being defined by an outer periphery of the central base portion, and each leading edge having at least a portion that forms a continuous curve with a radius decreasing outwardly toward a radial tip of the corresponding impeller blade, wherein the continuous decreasing radius curve of each leading edge is formed by a portion of an ellipse centered on the center axis, a short axis of the ellipse being equal to a long axis thereof divided by approximately three and one-half. Each blade extension is projected from the corresponding impeller blade opposite of the leading edge.