The ornamental design for a flowcontrol for a filter, as shown and described.
FIG. 1 is a side elevation of a flow control for a filter showing my new
design, the opposite side elevation being the same;
FIG. 2 is a front elevation thereof, the rear elevation thereof being the
same;
FIG. 3 is a top plan thereof;
FIG. 4 is a bottom view thereof; and,
FIG. 5 is a front elevation of the same at a reduced scale, the water
filtering pitcher being shown in broken lines for illustrative purposes
only and forms no part of the claimed design.