It should only cover about 1/3 of the floor. Temp gun it to see what the temps are on the floor right over it. Some will have more drop than others. 89-93 is good
What are you using to control your heat source?
does it matter what side of the heat tape is facing up or can either side face up??
the heat should only cover about 1/3 of the tub so they can thermoregulate. 90-93 for the heat tape for the hot spot and it should raise ur ambient temps up
A room full of empty racks and thermostats that have been unplugged.