Bacteria and the Nitrification Cycle - Nitrifiers or denitrifiers ??

["Stephan Mifsud" <valerandi at nextgen_net.mt>]

I said << Denitrification bacteria in a normal aquarium can
only
function in an anaerobic environment, and since the filter
is aerobic, the
only place they will function is in an anaerobic substrate.
>>

Bill replied <<I don't think so.  At least some of the
bacteria that convert ammonia to
nitrates require an aerobic environment.  That's why
undergravel biological
filters work (for a while) and why sponge filters are so
effective at
removing ammonia.  Both circulate oxygenated water past
bacteria.
An aquarium without anything but oxygenated water - no
filters, no substrate
- will also build up a colony of nitrifying bacteria and be
capable of
reducing ammonia.  Because of the limited places for the
bacteria to anchor,
however, it won't be able to convert very much. >>

You are talking about Nitrification not Denitrification!

As you said Nitrifiers usually require an aerobic
environment to change NH4->NO2->NO3 (+/- signs left out),
But I was talking about denitrification which is a reduction
process. Where NO3 -> N2 which is unavailable to
plants/algae. Diana Walstad showed how efficient this
mechanism is in getting rid of excess Nitrates in an
anaerobic substrate in one of the TAG issues.

To be fair there are some aerobic denitrifiers (eg
http://www.kuciv.kyoto-u.ac.jp/res98/ewq.html) but the
significance of these in a normal aquarium is debateable.

regards

Stephan




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