DSB w/Plenum Producing Bubbles

[ppurcell]

Hello folks,

I have been bothered by a very large volume of small bubbles circulating around my tank. I had assumed they were coming from the skimmer; however, while performing some maintenance today I had the pumps shutdown for a while and noticed that the bubbles were coming rather steadily from the substrate at a steady rate such that I could see at least a dozen or two rising continuously. When the pumps are on, these bubbles are prevented or signifigantly delayed in their ascent to the surface causing the tank to have a very high number of bubbles moving about the tank all the time.

So I don't remember reading about this phenomenon in any of the literature I've read on DSB's. Can anyone tell me what the gas in the bubbles might be? I would especially appreciate some tips on the cause and prevention or a means to manage them...

In case it matters, I'm have a 1.5" plenum with a 6" DSB of Special Grade Aragonite on it.

Thanks,

Phil

[Steven Pro]

Nitrogen bubbles would be my best guess.

[ANGRY JOHN]

of the two bubbles i could guess nitorgen like reefland sugested would be my first guess and that would mean that the plenum is working properly. why would you want to stop an ongoing denitrofication process if it is working properly. i could see the airbubles as being anoying but this is what it is supposed to be doing.

[Steven Pro]

I just had a few follow up questions. Is this a new sand bed? What kind of lights do you have? And, do you see any algae like films forming on the sand bed when the bubbles are coming from?

[ppurcell]

The sand bed/plenum was constructed over a year ago, however the bio load has only been present since early January. So I suppose it is a new sand bed. I am running eight 65W PC's over the tank (AGA75). About 2-3 weeks ago I started getting some short brown algae growing on the surface of sandbed, rocks and glass. It isn't growing on the rocks much anymore, but is still growing on the sand and glass.

The bubbles seem to be perculating up from everywhere, including bubbling up from underneath the rock structures. There isn't any obvious Cyano growth.

Obviously, I have no interest in stopping the denitrification process if that is what is producing the bubbles, but I don't recall anything saying this is a normal behavior of either a DSB or Jaubert system.

[Steven Pro]

The amount of bubbles does seem a bit excessive for nitrogen.

I asked about the lighting as sometimes excessive lighting produces oxygen bubbles, but I would only expect that with dual 250 or 400 watt MH's in this size display.

Cyanobacteria and dinoflagellates ocassionally produce bubbles as well.