Check out this video that I uploaded a few years ago on YouTube, if you follow it to the letter you should have no problems with incubating your clutches.
https://www.youtube.com/watch?v=F-wjmsV9gMw
My incubators are bone dry (no open containers of water) I never have to add anything to the nest boxes during the incubation period. Remember it's not the humidity inside the incubator that should concern you, but the humidity inside the nest box that will determine whether the eggs desiccate / dimple too early.
If you are still unsure of what to do feel free to call me anytime at 408-981-6694, I'm always glad to help.
Brian Gundy / For Goodness Snakes