a couple questions

[concept3]

ok, here is the situation. i recently purchased two crested geckos, i keep them in a 33 gallon tank with a screen lid. i have a 50 watt bulb on in the day and a 50 watt night bulb at night, i keep them on the ends of the tank so half of the tank is cooler. In the day the warm side of thetankisabout 78-80 and at night about 70, keeping in mind their is a cool side in the tank. My cresties are about 2 1/2 inches head to tail, just babies. i live in alberta so its quite low humidity about 40%. I mist them in the morning about 7, in the afternoon about 4 and at night, aabout 9 oclock, but inbetween these periods the humidity drops to about 40 is that ok? also i was wondering what kind of substrate for the babies? i was thinking topsoil or bed-a-beast which one is better? im leaning towards topsoil because the crickets cannot hide in it. If anyone sees anything wrong with my setup or can answer my questions i thank you for your input