Having troubles keeping right temps in tank

[Kaorte]

The snake is about 4' long, I have a digital and I use cocunut substrate.The tank is 3' long by 2' wide. Im not insulating the tank, how would I go about that ?
Thanx for the help !!!!

Mike

Does your digital thermometer have a probe?
You can get some foam core board from the drug store, cut it to size and cover the back and sizes of your tank.