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Re: HNO3 generation
> From: Jonathan_Kirschner at Energetics_com (Jonathan Kirschner)
> Subject: HNO3 in Planted Tanks?
>
> Paul Sears wrote:
>
> >As Steven says, if the KH is 2, you have no problem, and you
> >can probably use less. What a large KH _does_ protect against is the
> >effect of adding strong acids. If HNO3 is generated in your tank,
> >then it will use up the KH, and when it runs out......
>
> Under what conditions would nitric acid be generated in a tank?
If the plants don't use all the ammonia from the fish, then the
bacteria will oxidise it to HNO3.
> Is this due
> to the natural hydration of our ever-present nitrate ions?
The nitrate ions can't be _hydrated_, but they come as HNO3
in the first place.
> I can only assume that I stressed the fish by perhaps adding too much KNO3,
> too quickly, although the LaMotte still shows no nitrate residual in this
> tank either upon dosing or in the evening (I dosed in the morning). I know
> that the kit is working because It does show nitrate residual of a few ppm on
> my older 20 gal which has a much higher fish (and snail) population.
If it isn't being detected, it is being used, and can't bother
the fish. I suppose that if solid KNO3 went in the fish might eat it,
and that probably wouldn't do them any good. I know that Kevin's fish
would eat trace element mix, if given the chance.
> I do
> not use KNO3 in that tank because the fish are supplying adequate nitrates,
> and both the plants and the fish, including about a dozen cardinal tetras,
> are happy and healthy. I did notice, however, that the KH in that aquarium
> falls noticeably after about a week (I do weekly water changes). I assumed
> that this was due to the snails removing calcium carbonate from the water to
> make their shells. Is it more likely that the buffer is being used up by
> HNO3?
If nitrates are building up, then _some_ of the KH loss is due to
the HNO3. If you get 40 ppm NO3- (say) then the KH will be reduced by
32 ppm CaCO3 equivalent, about 2 KH. Do you _remove_ snails? If not,
they should be in a steady state, and will not remove anything from
the water (on balance).
--
Paul Sears Ottawa, Canada