How to best heat a tank?

[samw]

Hi guys,
I’m setting up a new tank to move my now almost adult Amazon Milk Frogs into.
They are currently in a 12x12x18 (30x30x45cm) exoterra with a heatmat underneath the base heating the substrate, this works fine and keeps the tank at the correct temperature.

My question is where do most people mount their heatmats in order to yield the best heat from them? I’ve heard that people put the mats behind the exoterra background but surely that would lose more heat than gain it?
The new tank is 60 x 45 x 60 cm / 24” x 18” x 24” exoterra so much bigger and I want to be able to heat it as effectively as possible. Its needs to be around 70-85f/22-30c to give to an idea of the temperature I’m trying to achieve!
Thanks

[Mentat]

If using heat mats; you want to place them in the sides. Placing in back with an insulating piece of styrofoam or custom background in front of heat source is a bad idea. Placing heat mat under tank works fine with reptiles; but no so with frogs. Unless you are talking about a lamp produced basking spot; mid to high 70s is fine for Milk Frogs. They will tolerate 85F; but you do not need to get whole enclosure there. Another option to heat pads is using heat tape connected to a controller. Good luck !

[samw]

One thing I'm just considering. Is it more important to base your temperature readings on air temperature or surface temperature? I have both a permanent air probe and a hand held laser thermometer so there is obviously a difference between the readings.