Welcome to the site. Great advice and some really funny folks here. I started out exactly the same way as you (30 gallon tank). Lots of people do. I found it so much easier to maintain humidity in a twenty long than a thirty. And, the key for me was to cut a piece of plexiglass to fit into the recessed top of the tank, and drill holes in both ends. This makes a tank more like a tub and helps keep in humidity. I have a bunch of different pieces of plexiglass, some with more holes than others. By just changing plexiglass tops I can regulate humidity during shed cycles etc. And the cool part is that the screen cover can just be placed right over the plexiglass.