I have a 20 gallon long tank that has a locking top and locking feeding door within that top. The humidity stays where it needs to be so far, and the ambient temp is correct because it's been hot and humid. In the winter the ambient temp will be ok because we keep the house hot and have ceramic heat emitters if needed. There are several ways to raise the humidity in a screen tank top like a bigger water bowl, covering some of the screen, adding a second bowl, plus misters and things...