i have been reading, and it was said that a bight uvb bulb isn't needed. i use it to help keep the temp up. i have a 20 long, with 1 uth on the side, and one uth under the tank itself. its hard for me to get the temps above 90. That is with on eof those stick on temp gauges. the temp is its highest with the lamp on but drops to 84 or so when off. Should i get a digital thermometer with probe before worrying, or go and get a night bulb and keep it on all the time? thank you