As much as I love glass vivs they can be a pain. So far what has helped me has been using eco earth as a substrate. It holds humidity around 60-80% if not higher depending on how saturated it is. When it is lightly damp it holds my humidity around 60%+ and so far it has been working wonderfully. This is in a 40 gallon breeder too with a screen top and no covering while I work on making a plexiglass cover for the screen.