dkeller_nc
New member
tmz: Just a minor note: there's no such thing as a "facultative aerobe". Bacteria are either obligate aerobes, facultative anaerobes, or obligate anaerobes. The usage of "facultative aerobe" has showed up in web postings and such over the last 5 to 10 years, but it's not an accepted term by the scientific community. Not a big deal, but if you want to use the correct terminology, the above is right.
Regarding dinitrification, it is quite true that bacteria will not use nitrate as an electron acceptor in the presence of oxygen, so dinitrification requires at least anoxic conditions. But denitrification is carried out by both facultative anaerobes as well as obligate anaerobes (different species, of course), so it will take place in both anoxic and anaerobic environments.
d2mini: To answer the question on "how do you change/add the mud if it's under sand/gravel", what I did in my freshwater riverine tank was to remove the fish, then dug out about 1/3 of the total tank bottom area to the bare glass. Then I replaced the layers with fresh mud & sand, replanted the vegetation and replaced the fish once the water had cleared up. Not exactly a fun way to spend a Saturday, but you only need to do it about once every one or two years depending on the plant density.
Regarding dinitrification, it is quite true that bacteria will not use nitrate as an electron acceptor in the presence of oxygen, so dinitrification requires at least anoxic conditions. But denitrification is carried out by both facultative anaerobes as well as obligate anaerobes (different species, of course), so it will take place in both anoxic and anaerobic environments.
d2mini: To answer the question on "how do you change/add the mud if it's under sand/gravel", what I did in my freshwater riverine tank was to remove the fish, then dug out about 1/3 of the total tank bottom area to the bare glass. Then I replaced the layers with fresh mud & sand, replanted the vegetation and replaced the fish once the water had cleared up. Not exactly a fun way to spend a Saturday, but you only need to do it about once every one or two years depending on the plant density.