I just tape the base of the probe cord to the bottom of the tub/tank about 2" away from the UTH using insulated duct tape (leaving approx. 6" of cord until the probe is where I want my UTH to rest). Then I place the UTH in position and use HVAC tape on the three sides that do not contain the wires. This seems to be a secure enough fit (almost pouch-like) that the probe is snug but still allows for a little air flow. I also am able to re-check the position of the probe when I remove/clean the hide by moving the substrate to see through the tub (though I have never had to re-adjust)!