We just got our first rack. We got a 6 shelf 15/32qt (sterilite) rack with flexwatt belly heat. We set it up with the proper tubs and placed the probe for our thermostat directly on the tape and secured it with foil tape. There's a lip on the tubs and a ledge where the heat tape goes (picture)


I have the thermostat set to 100 degrees but only getting 86-88 degree readings on the bottom of the tubs.
Should I continue to turn the thermostat up, or try to loosen the tape so it comes up a bit?
Any advice is appreciated!