Whenever mine come up for air, the best they typically do is about a half inch out of the water, although since they have such a jumping reputation, I think they can probably go higher. I wouldn't worry about them bumping the lid, that's what it's for. ;D Their little noses can take a learning experience. Just so long as they don't do it over and over.
Robert Falcon Scott - Red salamander HM plakat
Passed on- Friedrich "Freedy"
Four African Dwarf Frogs - Dorkus, Sporkus, Baron(ess), and Bubbles!