Hi all,

In my sand bed I see little air bubbles approximately 1/4 to 1/2 half inch
deep from the surface of the sand on the glass. Is that de-nitrification
going on? I thought that this occurs deeper in the sand bed?

I have about 3-4 inches of sand on my tank and was hoping to benefit from
anaerobic activity, however right now I am not sure as to what those bubbles
are. Trapped air... or actually nitrogen.

Any ideas?

TIA

Steve