hi they may have it between monday and wedsday but im online here now and i can get it from petco cheaper it is 169.00 dollars at petsmart and petco has it on sell right now 138.00 shipping and all is only 144.73 so im thinking about going and shipping it i need to know right now so i can order that too what size uth would i need. i found a 10" to 11" will that work?
"1/3 the length and nearly the width" does not equal 11 x 11 inches. You say the Exo Terra tank is 36 x 18 x 12 inches high.
So you will need a UTH measuring 12 inches wide x 18 inches long. Maybe a combo of two of UTHs. Size up a bit rather than down. Your thermostat will moderate the diffence.
How about figuring out how to use Flexwatt Heat Tape for this area?
Check post #44 following the leo caresheet for an introduction to Flexwatt Heat Tape by the Beanfarm Herp Supplies. Hopefully someone can guide you on that project.