Raising temps in a tub

Well currently im keeping my ball python which is roughly two feet long now in a 16 quart tub. I have zilla thermostat and I put the probe underneath the snakes warn hide and set it for 90 degrees. I also have a thermometer with a probe underneath the hide also. The problem im having is the tubs overall temp is in the upper to mid 70's even though inside the hide it 90 degrees. should I just turn the thermostat up until the overall temp of the tub reaches the 80's even though the hide temps might be in the 100's? My substrate is paper towels by the way. Sorry for the long post lol

No dont do that! the temp inside the tub will alaways be very close to your ambient temps in the house. You either have to raise your house/room temp or move the tub away from air circulation like A/C.

hmm ok i guess ill look into getting him a small heater

If the tub is not in an enclosed cabinet or a room heated warmer than the rest of the house, the tub will always seem cooler.

Try a tub with less holes punched in it, build a cabinet to enclose the tub so it just slides out, or make your warm side take up at least 1/3 the tub to compensate. IE, get a bigger UTH etc..

You do not want to just raise the temp. They do not always care about temps and can be burnt or die of long term heat exposure.