The ornamental design for a watertank for indoorplant cultivators, as shown and described.
FIG. 1 is a front perspective view of the water tank for indoor plant cultivators showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a perspective view thereof in a condition that the cover of the claimed design has been closed; and,
FIG. 9 is a reference view showing the state of use in which the claimed design is being installed at the bottom part of the indoor plant cultivators.
The broken lines depict portions of the water tank for indoor plant cultivators that form no part of the claimed design. The portions of FIG. 9 drawn in broken lines show environmental structure only and form no part of the claimed design.