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Re: Ammonia vs. Nitrates

K9AUB wrote;

> I don't know how you could reduce biological filtration long-term, nor why 
> you would want to do it.  Nitrifying bacteria will grow everywhere in the 
> tank, and will reach quantities capable of handling whatever ammonia load is 
> present.

You might want to do it to promote plant growth.

Nitrifying bacteria are relatively rare critters in natural environments
(or so I've read).  In biological filters we give them a steady supply
of food and specialized living quarters without direct competition, so
they thrive.  Without all that help they may not be so competitive with
plants.  Present yes, but I don't know if they would really compete very
well with the plants.

> Removing lava rock, ceramic rings, etc., would cause a temporary 
> ammonia spike, but in less than a week bacteria would catch up by growing on 
> other available surfaces.  In other words, your plan is not a long-term 
> solution.  Are there fish in the tank?  Deliberately triggering an ammonia 
> spike would be very stressful to them. Some fish (SAE's for example) simply 
> cannot tolerate ammonia spikes at all.

This is safe advice, but I'm not sure how true it is.

When I first started shutting down the biological filtration on my tanks
I monitored ammonia levels fairly closely.  I never did see an ammonia
spike.  So in the last few tanks I shut down the filters on I didn't
even bother to check.  I eventually shut the filters down on 5 of my 6
tanks and lost no fish in the process.  I did lose part of a group of
congo tetras out of one tank over a period of a couple months, starting
about 6 weeks after I took filtration off their tank, but I was never
sure whether or not I should attribute that to the lack of filtration.

The toxicity of ammonia is pH-dependent.  I don't have the table with me
right now, but my recollection is that at a pH near 7 or lower (typical
of a CO2-injected tank) you could actually have a fairly high ammonia
level without risking your fish.

The "ammonia vs. nitrate" debate has come up over and over on the list. 
I remember that a few years ago someone reported that they fertilized
with urea crystals, which I think they added to the substrate.  They
reported no problems.  The Jobes spikes of which I'm so fond contain
urea.  Urea hydrolyzes to ammonia+CO2, so in effect all of us using
Jobes spikes have been adding ammonia to their tanks.  Admittedly to the
substrate, where it's likely to stay if it's put in the right place.

Can anyone else report experience fertilizing their tank with urea, or
other forms of ammonia?

Roger Miller