I have tiny, clear bubbles in my tank. They seem to be coming from the bottom of the tank. They are free floating, going from bottom to top of tank, except for the hundreds that are covering a large piece of kenya tree coral. They were there yesterday afternoon and went away but now they're back. Any ideas???

doubtful its coming from your sand... algea can produce bubbles... sometimes... if its really really bad. but youd see the bubbles on the algea. you have microbubbles from your return or something?

No micro bubbles that I can tell. They are across the whole tank. No sign of any algae. Did upgrade lights the other day. From 4 t5 to 8 t5. Added some cheato and pods but nothing else. Everything looks good and healthy.

We used to have bubbles that would escape from the sand for a period of time when we set up our first tank.

After a while they just stopped.

I always assumed that it was sand that had settled.

hmmm. picture?

not sure what it could be... its just neverending bubbles rising from the sandbed? there isnt like... an undergravel filter or anything Im presuming, no new sand added.

No under gravel filter. I did move some rock a little the other day. They slowed down again last night and there weren't any this am when the lights came on. I'm on a 24hr shift so I'll have to wait until tomorrow to see.
Everyone and every thing seems happy.