After receiving no real answers from the forum, I added the following additional heating to my leos tank. first, the original heat source is a Cobra UTH 10-20 gal size with my geckos in a 20-long tank. Normal 3-season temps are perfect with the warm end at 88-90 days and around 75 nights - with the UTH on days and off at night. This winter, temps have lowered approx 10-12 degrees. First, I tried using the UTH 24/7, but felt that the daytime temp is too low. Temperature is approx 76-80 with the UTH only. I added a porcelain 5.5" clip lamp with an ESU 50watt red heat bulb on a timer for daytime use only. This bulb is not a spot or reflector type bulb - has a shape of a standard incandescent bulb. It is a true infra-red bulb with the rere-red earth coating. This bulb does not give off much heat - just a gentle subtle warmth. It adds about 5-8 degrees to the warm end takes the chill out of the air in the enclosure overall. The geckos seem to like this added warmth. and are more active. I will try a higher wattage heat bulb if it gets colder and report my results. Conclusion...this is a lower heat output than I desired, but may actually be ideal with the UTH. I will use this heat lamp only days with the UTH on 24/7. Sorry for the long post - hope this helps others in heating their geckos enclosure! Happy Leos.. RR

