This is all hearsay, so don't assume this is right, but...
I hear the reason that DSB
's work is that the bacteria in the lower portion of the sand does not get any circulation to speak of, so the oxygen all gets used up and they somehow supplement it with nitrates. Otherwise the bacteria does not process the nitrates at all.
If this is the case, then you know your DSB
is doing its job in some fashion because your nitrates went down. In my FOWLR
they only go up except for water changes.
Also, if that's accurate the bubbles against the glass would be in no way caused by denitrification.
Protein skimmers, as I understand them, don't remove nitrates, but remove disolved organic compounds from the water, which somehow promote or produce nitrates.
92-gallon corner tank, 100lbs of LR
, 140lbs of sand, 250watt 10,000K MH
, 110watts of actinic PCs, Mag 7 return, custom refugium, AquaC EV180 w/ Mag 5
Female lyretail anthias, eyelash blenny, tomato clown, saddleback clown, firefish goby, 2 sand-sifting stars