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Nitrogen use in filterless tanks

James wrote:

>Finally, any of the nitrogen input which was already in the form of nitrate
>would be ignored by the plants in the presence of either  NH3 or NH4+. So I
>guess even a filter less tank would benefit from water exchange (to export
>the nitrate) or de-nitrification (in the substrate or in a separate
>bio-filter???). Comments, anyone?

I think there are other good reasons for doing water changes besides
nitrate export.  But as far as the nitrate is concerned, even with a fairly
hefty stocking level, in my high light/strong growth tanks the plants use
all available ammonia/um, _and_ eagerly slurp down the extra nitrate I feed
them on a regular basis.  

In my low light/slow growth tanks, nitrate levels often hover between 15-20
mg/l.  I suspect that this would go higher if I didn't do intermittent
partial water changes.  Even in these tanks, I am pretty sure that the
surface area on gravel, rocks and plants is enough to support adequate
colonies of nitrifying bacteria to convert the leftover ammonia/um to
nitrate.  I think that because I often neglect the OPF's on those tanks for
long enough that most of the water is bypassing the clogged filter material
and running around the edges. (I told you I don't worry about filters much
;-)  As with the high light/strong growth thanks, the water is clear and
fish and plants  continue to thrive.


Who is concerned that she may be reported to the S.P.C.N.B. (Society for
the Prevention of Cruelty to Nitrifying Bacteria)