A question and an answer

>From: gtong at sirius_com (G.Tong)
>Date: Mon, 20 May 1996 17:20:20 -0700
>Subject: Re: Ammonium
>>Plants generally will not use nitrates due to the amount of energy
>>required to extract nitrogen from the compound.  They much prefer
>>ammonium as the nitrogen is less tightly bound.  By removing the
>>biowheel, there are less nitrifying bacteria to convert ammonium and
>>the conversion goes slower, giving the plants a better shot at using
>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.

Ammonia is what fish excrete.  However, in acidic solution (higher H+
concentration), the reaction: NH3 (ammonia) + H+ > NH4+ (ammonium).  The
amount of ammonium produced is usually only dependent on the acidity of the
water as ammonia is usually not the limiting factor in the equation.  That's
why in African cichlid tanks, the water quality goes bad so quickly.  I
think my reasoning is right but anybody that's knows better will correct me :)

By the way, I have a question as well.  For people that use daily trace
elements (Dupla Drops or PMDD), do you leave the solution outside or in a
fridge?  I'm thinking about making a doser but I need to know if the trace
mix can stay outside for a week.