Ultratherm Viv Mats - is there really just one general answer?

I have read some articles here and seen polls about heating mats (as the best solution to provide warm/cold end of viv). However I have feeling there is still few questions unanswered. Is it the best solution for all kind of vivs? let me give you some examples...

let's have six different vivs:

a) small made of plastic (let's say floor projection up to 400x600mm (1.3x2.0ft))
b) medium made of plastic (let's say floor projection 400x600 - 500x1000mm (1.6x3.3ft))
c) big made of plastic (let's say floor projection more than 500x1000)
d) small made of glass
e) medium made of glass
f) big made of glass

and here are questions:
1) is heating mat the best solution for all vivs above?
2) is heating mat always better put under whole viv (not inside) for all vivs above?

why asking...

• I have read installation manual for Ultratherm Viv Mats and they describe both options (inside/outside installation). Also I have read waring if I use really hot mat (to reach proper temperature inside) under large glass area it may crack.
• There are available many sizes and different powers of mats... what if I buy "too weak" one for under viv installation? Is that mean using it inside is not a solution and I must buy bigger (and more powerful) one?

btw.: today I have received 414 x 274 mm / 22W Ultratherm Viv Mat for my 500 x 1000 glass viv. I hope it's good enough... Now waiting for thermostat... :)

In general a UTH of some kind is the best choice for a glass tank. Ultra therm is plastic coated and could be placed inside the tank but that is really unnecessary. Taped to the bottom on the outside and hooked to a thermostat is the customary way. Inside the tank it would have to be dealt with all the time for cleaning. Outside the tank it can be basically forgotten about once it has been installed.

first test results! I have plugged mat 12 hrs ago (just laying on a top of viv) and measured temperature (w/o any thermo regulation). Max I got on surface is 36°C/97°F... Is that normal? I have expected more...

...and see pics :):

http://i48.photobucket.com/albums/f2...H/P2234163.jpg

http://i48.photobucket.com/albums/f2...H/P2234169.jpg

http://i48.photobucket.com/albums/f2...H/P2234170.jpg