A ring impeller includes a central hub with a first row of vanes extending from the hub and a second row of vanes extending from the hub adjacent to and staggered from the first row of vanes. The vanes in each row are grouped to form adjacent vane pairs and a partition wall is positioned between each of the vanes within the vane pairs. A rib extends radially from the hub in alignment with the partition wall and is positioned between each vane pair. The bottom thickness of the partition wall is the same thickness as the rib. The partition wall includes a reduced material area at its forward and rear edges. The vanes in the first row are unevenly spaced and the vanes in the second row are spaced equidistantly between the vanes in the first row. The spacing of the vanes in the first row may be about 70% to about 140% of a spacing equal to an equal spacing. Some of the vanes may have a height that is less than the height of other vanes.