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RE: [APD] An observation

Jim Siedman quoted George Booth

>Dr. Alfred Gianascol, in "Water Chemistry in Closed System Aquariums"
>(1987), demonstrated that in a typical aquarium [without plants], the
>actual filter only provided about 15% of the total nitrification. The
>biofilm on the glass and gravel provided the rest.

I seriously question this purported finding.  If this were the case, it
would not be possible to move an entire fish load from one unplanted tank A
to another unplanted newly set tank B along with the existing biofilter from
A without seeing unoxidized metabolites shortly in the "new" tank.  But my
experience is exactly contrary to this.  I move stock and their filters with
some frequency (tank room rearrangement in process) and never see any
ammonia or nitrite.  My conclusion is that the nitrification bacteria reside
primarily in the biofilters which I moved with the fish.  Further, if new
fish are introduced into the original tank A, even smaller numbers or mass
than was previously housed there, and a competent biofilter is not added,
there will be unoxidized metabolites detected, which should not be the case
if bacteria sufficient for >80% of the former bioload were still present.

Nitrification bacteria should establish in the sites offering best
attachment with best delivery of oxygenated water containing nutrients
including the nitrogenous compounds they use for energy.  If these
conditions are not optimum in the filter over the conditions in the tank,
just what filters and setup were used for these trials?

The quote continues:
>So, you can safely assume that there are in fact huge numbers of nitrifying
>bacteria in even the most densely planted tank and that they will happily
>convert any ammonia/ammonium that drifts their way into nitrate. They DO
>compete with the plants for nitrogen and WILL generate nitrate.

I question the final conclusion here as well.  When doing comparable moves
as I mentioned above, the one source I cannot use for a stolen/borrowed
filter is the biofilter from a heavily planted tank.  These filters do carry
the nitrification bacteria sufficient to be well inoculated for starting the
cycle, but not in colony size to support the biomass in the tank without the
plants.  If there is competition for the metabolites, IME the plants win
over the biofilter routinely.  If the filter out-competed the plants
(forcing them to nitrate utilization), then the filter bacterial colonies
would be sufficient for the bioload of the fish, and that I have never
observed.  The inoculated filter will produce some nitrate, granted.  But
does not initially have sufficient colonies to oxidize the ongoing load.
There is doubtless some competition, but I see the balance rather heavily
weighed toward the plants.  In an unfiltered tank, I do not doubt that
nitrification bacteria will find and grow in sites which do serve, even
though a filter, if present, should provide a more hospitable situation.


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