A center tube and a central fluid supply tube combination includes a center tube body defining a longitudinal length, and a central reservoir. The center tube also includes an apertured annular wall extending axially the majority of the longitudinal length, and a first annular solid wall extending axially from the apertured annular wall. A central fluid supply tube is disposed in the central reservoir, and includes a second annular solid wall that is radially surrounded by the apertured annular wall of the center tube. The second annular solid wall defines a supply passage with a fully circular flow flux.