Bio-chemistry question re dsb's and anoxic bacteria

[Aquarist007]

Hi Guys:
I wonder if you could help us out on this thread. It started out with a discussion on why dsb's eventually fail.
It is related to a concept that I have learned from this site that
anoxic bacteria---live in the deep areas of sand bed or deep cores of live rock--these break down nitrates to nitrogen gas and complete the nitrogen cycle.
However the discussion is shifting to talk about how nitrates are actually chemically broken down so I am calling upon the experts in this forum to help us out:D


http://www.reefcentral.com/forums/showthread.php?s=&postid=14638711#post14638711

[Randy Holmes-Farley]

Seems like it moved on to being a discussion of actinic lighting now. :D

[Aquarist007]

<a href=showthread.php?s=&postid=14639840#post14639840 target=_blank>Originally posted</a> by Randy Holmes-Farley
Seems like it moved on to being a discussion of actinic lighting now. :D

thanks for looking in Randy

Do I have this explanation correct?

aerobic bacteria--surface of rocks and sand bed--break down ammonia to nitrites

anerobic bacteria--crevices of rock , first inch of substrate--break down nitrites to nitrates

anoxic bacteria--deep in the live rock and in the deeper layers of the sand bed---break down nitrates to nitrogen gas.

[bertoni]

There's a number of possible places where nitrate could be processed into nitrogen gas and other byproducts. One such place could be the inner layer of a microbial film on live rock, for example. Nitrite conversion to nitrate occurs in aerobic areas, or at least area with oxygen available, since the process convert NO₂ to NO₃.

The "deeper" parts of the sandbed can be fairly shallow, depending on the animals, consistency, and other factors, and I don't know of any data on how much nitrate is reduced in the average aquarium setup.

[Aquarist007]

<a href=showthread.php?s=&postid=14642634#post14642634 target=_blank>Originally posted</a> by bertoni

The "deeper" parts of the sandbed can be fairly shallow, depending on the animals, consistency, and other factors, and I don't know of any data on how much nitrate is reduced in the average aquarium setup.

thanks Bertoni----
I was referring to dsb's or remote dsb's of between 4 -7 inches.

Are there not anoxic bacteria that live in the deep levels of these sand beds that reduce nitrates to nitrogen gas?

[Aquarist007]

<a href=showthread.php?s=&postid=14639840#post14639840 target=_blank>Originally posted</a> by Randy Holmes-Farley
Seems like it moved on to being a discussion of actinic lighting now. :D

I should have pointed your attention to this thread:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1593453&perpage=25&pagenumber=1

your thoughts would really be appreciated.

Scott

[Randy Holmes-Farley]

Yes, I've seen that thread, but I did not think there was any new revelation there that would be something a reefer would act on. The number of different processes involving the nitrogen and carbon cycles in sand beds is large, and many have been known for a long time.

Sand beds can obviously work in some cases, and often are inadequate to keep nitrate as low as some folks want. Beyond that I think that trying to understand/speculate on what exactly is happening in a sand bed as a function of depth in any particular reef setup is quite difficult in the absence of actual experimental data for the same sand materials, water chemistry, life forms, etc.