Keeping UTH flush to bottom of DIY sterilite tubs

[Geminiluna]

The heat tape gets taped to the shelf, not to the tub

The bottom of the tub is somewhat recessed, and so if the UTH is taped to the shelf, it will not have contact with the bottom of the tub. And now that the tub is bowing upward, it definitely won't have contact with the UTH. Is that ok? I realize I may need to crank up the thermostat above my target temp to compensate, but just wanted to know if the gap between tub and UTH is any issue.