Micro-bubbles?

[Northstar24]

I have a bunch of little bubbles on the surface of my sand, I am assuming two things
1)They're the micro-bubbles I've read about online and in my saltwater books
2) As micro-bubbles - they're bad news

I've examined my setup and I'm not sure where they are coming from. My returns are fully submerged, and the skimmer does not appear to be sending bubbles back into the return chamber

How worried about these should I be, and if its not the return lines bubbling at the surface and its not the skimmer, where else should I be looking for the source?

 

[BL1]

If they're just on your sand bed and not in your water column then, I'd say you have an algae outbreak coming. That's usually how they start in my tanks.

 

[Northstar24]

I guess that would make sense, as I haven't really had a large outbreak yet, despite a full cycle and plenty of fish to fuel the outbreak