Glass tanks work ok but you may need to add another heat source along with the UTH.
I would invest in a thermostat as soon as you can. You can regulate the temps in the tank better with it and you can plug in an extra heat source like a ceramic emitter.
What else can I add with the UTH? Once I build my cage set up should I have 2 pieces of flexwatt per rack one on the hot and one on the cold side? Thank you again guys