The ornamental design for a water-softener filter wrench, as shown and described.
FIG. 1 is a three-quarter (approximate) front perspective view of my new design for a water-softener filter wrench;
FIG. 2 is a top view thereof;
FIG. 3 is a side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a bottom view (handle side) thereof;
FIG. 6 is a three-quarter (approximate) front perspective view of a second embodiment of a water-softener filter wrench of my design as shown in FIGS. 1-5; and,