Air Stones and Air Diffusers

[Becca]

I still can't seem to keep my air stones and air diffusers working in my orchidarium. I have tried both, and the air diffusers seem to work better, but stop bubbling after a short while. My rubber lining tray won't hold enough water to completely submerge them so I am sure this is the problem. Are they really something I need? Are they just for humidity or for keeping the water in the liner from getting yucky, like it does. Any suggestions? I didn't get the sponge that was supposed to come with the set up, would this work in place of the air stones for humidity? If so would any regular sponge work? I don't have much space or hight to work with. TIA!