This is a classic case of cyano bacteria. Diatom looks a lot like cyano sometimes, but they don't usually hold bubbles inside. Bubbles come from photosynthesis.
The treatment for cyano is pretty much the same as diatom except for reducing silicate which helps cutting down on diatom. What futureeyedoc prescribed is correct for cyano, too.
The common cause is the high nutrient level in your water. If you are still using tap water, I'd switch it to RO water. I suggest that you test your water for NO3 and PO4.
If you don't have any light demanding coral such as SPS or tridacna clams, turning the light off for 4 days after a good water change would be the cheapest thing to try. A light case of cyano will be treated easily this way. Some people do this once a month with a good success. I recall that there was a long running thread on RC a year or two ago.
However, if this does not make a dent, you should consider using Red Slimer Remover. It's a reef safe antibiotic treatment. This should get rid of cyano pretty quickly. However, the result will be temporary unless you take care of the underlying cause (a high nutrient issue).
Granular ferric oxide products, such as Rowaphos and Phosban, or a UV sterilizer works, but they require some initial investment.
HTH,
Tomoko