I am expecting to get my first group of D. auratus next week so I got my tank set up, planted, etc... this week and although I have no problem keeping the humidity around 80-90% my temps hover right at the 68-70 mark. Most forums I read said that they don't use any type of supplemental heat, other than their lights, but i'm worried that the tank is too cool. What is the best method of raising it just a few degrees? (I don't want the little guys to be too cold but I certainly don't want to cook 'em)

Oh, and if it helps: I am using a an Exo-Terra medium terrarium (18" by 18" by 24" or about 33 gallons) With a custom made glass top. And currently the Exo-Terra hood with two compact florescence (the repti glo 5.0 and the repti glo 2.0) I didn't want to get a spot unless I needed it out of fear of being too hot.

Much appreciation!