Re: [Killietalk] Nitrogen, nitrate, nitrite and ammonia

[Wright Huntley <whuntley at verizon_net>]

Charles Harrison <charles at inkmkr_com> wrote:

At 8:31 PM -0800 11/24/04, Wright Huntley wrote:

>> Hi all, Some recent apparent disagreements, here, prompt me to ask
>> what the definitive answer really is.

>> My understanding is that ammonia (not ammonium ions) and nitrites
>> are toxic to our freshwater fishes. Ammonia damages baby fish gills
>> at levels down around 5-8 ppb (yeah, that's parts per billion),

> And yet our Killies do well in a peat brown water which may be
> several % ammonia/ammonium . . .

If it is peat brown, the pH is unlikely to be high enough that any
significant fraction is as ammonia, and ammonium ions are as harmless as
chloride ions. [Ammonium/ammonia test kits are likely to measure the 
adsorbed ammonium/ammonia at the CEC sites, too, which probably cannot 
harm the fish.]

That said, I never knew about the ammonium in peat, as I always boil and 
repeatedly rinse my peat and all the ammonium sites are replaced by the 
Ca and Mg from the harder tap water. :-) The nitrogenous stuff all went 
down the drain. This seems to keep all the best anti-bacterial qualities 
of the peat but reduces how "hot" and reactive it is. [Most of the lime 
added to virtually all agricultural peat, but not on the label, is also 
washed away.]

>
> Hydration and hydrolysis and ionization and free reactive molecules
> would answer your questions Wright, along with life form specific
> susceptibilities. So we need ionization constants, dissociation
> constants along with susceptibility to explain all this water
> chemistry.

What would help we non-chemists is a guideline as to when
nitrates become toxic to killies at what temperature. That is what I 
haven't been able to find. My own experience has been that nitrates are 
harmless in surprisingly strong doses, as I have ODed planted tanks with 
KNO3 any number of times without seeing any fish stress. Maybe I failed 
to notice a reduction in eggs or fertility. I'm not sure.

>
> How can we explain so many fish doing well in CO2 saturated water?
> The plants seem thrive in it But don't the fish need O2?

CO2 in solution has essentially no effect on the amount of O2 in that
same solution, AFAIK. Aren't they almost totally independent?

It's not like CO where the same hemoglobin sites can be filled with the
CO and prevent uptake of O2, to suffocate the recipient. [Same process
as nitrite (NO2) poisoning.]

What I would still like to know is what is a safe level of nitrates and
nitrites in a typical (if such exists) killifish tank. There are lots of
variables, like salinity, temp., etc., but some rough values would be
nice. The damage levels of ammonia were carefully measured and published
in Spotte's _Fish and Invertebrate Culture_. Those agree well with my
experiences. I have not seen similar results for nitrates. Nitrites have
been treated in some aquaculture literature, but my sources, out here in
the boonies, are very limited.

I'm sure it is species specific, as many goldfish and carps tolerate
stuff that killies hate, but the effect on our killifish needs to be
better defined, IMHO.

Wright

--
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
                      760 872-3995

"The merit of our Constitution was, not that it promotes democracy, but
checks it." --Horatio Seymour

               http://www.libertarianism.com/



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