Thanks guys! I worried about the breathing thing a little too, but it doesn't fit all the way over, it has an inch-or-two gap in it that we can optionally close up with a plastic seal. We closed it up at first but the tank got really fogged up and I started to worry, so now we keep that part open except for feeding time. The average temperature in there in the daytime is 80 and the humidity is around 80 too. I will be looking for a screen lid though, since neither pet store we went to had big enough ones in stock! My tank is (in inches) 36long x 18wide x 17tall so no clue what that equates to in gallons (I'm a litres gal at heart). I keep wanting to change around their habitat and buy them new stuff so I think my nesting instinct is kicking in haha