Apparatus for washing and/or dewatering cellulose pulp is disclosed including a movable permeable surface in a pulp transportation chamber having a chamber gap above the movable permeable surface, a pulp distributor for distributing pulp onto the movable permeable surface, a throttle having a throttle gap width and an adjustable throttle adjuster to remotely adjust the throttle gap width so that a volume of pulp flow into the pulp distributor is equal to or greater than the volume of pulp flow out of the distributor during operation.