Bubbles rising from DSB

[Bushman]

Can someone explain what these periodic bubbles are that rise from my sandbed. Is it something being expelled or what? Also, it is normal, I hope! Thx.

[BlAcK_PeRcUlA]

http://www.rshimek.com/reef/sediment.htm

this explains everything about DSB's

[SBGRAD24]

They are the nitrates in your tank bubbling out as nitrogen gas. It means that your DSB is working.

[BonsaiNut]

It is a natural process of the denitrifying activity of your deep sand band. Within the anaerobic areas of your DSP, the bacteria break down nitrates for oxygen, and release nitrogen gas as a byproduct. The bubbles you see are nitrogen, which makes up around 70% of the "air" around you.