Re: Ammonium

> From: gtong at sirius_com (G.Tong)
> Date: Mon, 20 May 1996 17:20:20 -0700
> Help. Where does ammonium come from? I thought ammonia was what the fish
> secrete. If so, something must first turn ammonia into ammonium ... Where
> does that something come from? TIA.

Ammonium and ammonia are in equilibirium in the aquarium.  The
relative amount of each depends on pH and temperature.  At a pH of 7,
the great majority of ammonia/ammonium is in the form of ammonium
(Neil Frank will post the details).  This is lucky for us, since even
a small amount of ammonia is toxic and ammonium is a "good thing".
Aquarists keeping Rift Lake cichlids at pH 8.3 aren't so lucky. 

> A related question: when one has a biofilter in a heavily planted tank,
> would the bacteria and the plants be in competition? 


> If so, who gets what first? My guess is the filter gets the ammonia
> first because it's puming the water through while the plants stand
> around waiting. Thus, the plants are more likely to get only
> nitrates--which we now know they have a harder time making use of.

Yes, filters are more aggresive feeders than plants.  However, if a
fish "takes a leak" near a plant and that plant is paying attention,
so much the better for the plant. :-)

I would suspect, however, that all the ammonium is not converted to
nitrite/nitrate on the first pass through the filter and plants may
get a second chance at a lesser amount.