UTH not hot enough on inside of tub?

[Maymay]

UTHs are not meant to warm the ambient air but to create a hot spot. Please put your UTH back to a safe temperature. If you need to warm your ambient, look at CHEs, RHPs, warming up the room, or a space heater. You can even insulate your tub.

I'm not using it to warm the ambient temperature. The probe is measuring the temperature of the basking spot, which is not getting warm enough.