bubbles in my sandbed

[JKDMan]

idk what causes it but i have bubbles forming in my sand bed
when i clean the glass i move the sand around and let the bubbles out

any ideas as to whats causing this

 

[FinalPhaze987]

i could be wrong here but i believe its caused by anerobic bacteria converting nitrate to nitrogen gas...the bacteria live in the absence of oxygen so they get it from nitrate molecules..once the O2 is extracted from NO2 your left with just nitrogen, which eventually floats to the top and exits via gas exchange through surface agitation.. so its a good thing.. i was wondering the same thing when i saw the bubbles in the sandbed as well as the live rock...

 

[Len]

Yep, could be bacterial denitrification (NO2) or algae photosynthesis (O2) byproducts.