With moss, heavy mineral or chemical content in water spells doom. Generally, if the water is safe to use with darts frogs, it’ll be fine for moss. Spring, distilled, or reverse osmosis water is safe. Some mosses, especially those traditionally used in aquariums such as java or riccia (technically a liverwort), need wet, almost saturated conditions. Most other mosses, such assheet moss, shag moss, or mood moss, actually prefer a bit of air movement, and a chance to air out between misting. If you’re not sure what the moss prefers, it’s a good idea to split the moss into several sections and try keeping it in different conditions in the vivarium.
Java moss, typically grown in an aquarium, requires more water than many other mosses.