The first thought that runs through my head when people say "diatoms" and "bubbles" in the same sentence is dinoflagellates. I'm not familiar with your tank as it sounds like some of the above posters are, it sounds like maybe your tank is still cycling, or it is still really young? If the tank is super young it would be unlikely that dinos would already be a problem, but it's something you may want to look into. Also, keep in mind that if they are indeed just diatoms (be glad it's not dinos haha) that you want to double check your "nutrients in" (feeding, source water, etc) and make sure the diatoms don't persist for more than about 10 days or they will certainly continue into more noxious algae.
Dinoflagellates:
