I would recomend if your not going to have a thermostat to get a digital thermometer and place the probe on the substrate (just lay it on the top on the hot side) so that you can more accurately monitor the temp's. Depending on the substrate that you use if its going to be papertowels or slate rock or tiles it would be best to go to home depot and ask them for a lamp dimmer switch. You plug your UTH into the dimmer switchs plug and that way you can turn the UTH up or down depending on your temps. I would never turn your UTH off at night either as your gecko really needs to have a hot and cool side constantly to self regulate body temps. Low temps can cause your gecko to get sick. For now thats the best advice i can give on heating.
Good luck,
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Mike & Wendy 
2.0.0 Siberian husky, Jackrussel/schitzu
0.0.1 Lepard Gecko
0.0.4 Beta's
3.1.0 Warm blooded life sucking spawns.