If you are not utilizing the backwash function, you must install a 1/2-inch plug in the backwash port.

Directs water downward through the media to pack the bed back down and flush out any remaining debris or "fines" before returning to service.

Most manual heads feature a handle that rotates between three or four primary settings:

Reverses water flow (upward) through the media bed to lift and loosen trapped sediment, flushing it out through the drain port.