The bubbles doesn't actually help keep eggs alive. It's just nature's way of "hiding" fry and/or keeping them together until a certain point. Without bubbles, fertilized eggs will survive. The main issue is keeping eggs clean from mold - which daddy does each time he mouths them.
Endurance (bubbles) depends on the. . . thickness of (sorry, don't know the right term) . . . the water surface. Thicker, means stronger bubbles. But you don't want the water to be too thick. To avoid bubbles from popping too soon, you can cover the tank.