Keying removable storage tanks 110, 112, and 114 may entail configuring removable storage tanks 110, 112, and 114 such that they may be able to fit within tub 116 in a single orientation and configuration, such as having them be differing shapes (e.g. differing heights, widths, depths, rectangular, and spherical) such that the differing shapes designate a particular location for each of removable