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Re: Aquatic Plants Digest V3 #669

On Thu, 26 Nov 1998, James Purchase wrote:


> If one tank is set up using Dupla's products and another is set up using,
> for example, Aqualine Buschke products (substitute Amano, Seachem or any
> other full-line range here, as you wish), and both tanks are maintained in
> the same fashion and followed closely for a year, is there nothing of value
> (scientific or otherwise) which can be drawn from a comparison of the two
> systems at the end of that time?

I think there may be some valuable comparisons, but they must be done with
caution.  When or if differences are found, it seems to me essential to
follow up on the reason for the difference before detailed conclusions can
be drawn.

> Surely any gross deficiencies or excesses, if they exist, would become
> visible within that time frame. Even with the unique nature of indivdual
> tanks, if one product line failed to provide sufficient Magnesium
> (substitute the essential element of your choice here) then over the course
> of a year surely that deficiency would manifest itself in that particular
> tank. I realise that diagnosing nutrient deficiencies can be problematic but
> even if one was unable to pinpoint just exactly which nutrient was in short
> supply (or excess, as the case may be), an observer would be able to say if
> one product line was meeting the plant's needs as well as another product
> line. At least for THAT particular aquarist, in THOSE particular tanks. And
> would nothing be gained from such a study which could be of use to other
> aquarists in THEIR tanks, under THEIR own unique circumstances?

One possible problem is that different people have different water
chemistry, and the system that works best for your conditions may not be
the best for mine.  For instance, my tap water provides rather little
magnesium or calcium and about 91% of the cationic charge in the water is
accounted for by sodium.  The preponderance of sodium may actually
aggravate the already low levels of calcium and magnesium.  As a result, a
fertilizer regime that provides a lot of calcium and magnesium may be the
best for me, while under conditions of your tank, the best system might be
the one that promotes early root development, or something else entirely.
> Would anyone like to comment on HOW (or even IF) different
> product lines can be compared in a manner which would meet the requirements
> of "science" while at the same time be understandable and useful to us as
> hobbyists?

Aside from the general need for tight controls on such an experiment, I
think it's important to follow up on any differences that appear and
deterime why they happened. That is likely to be fairly expensive, as it
might call for plant tissue analyses and possibly for microbiological
surveys of the tanks.  Without that follow-up the conclusions may be
limited to simple generalizations about (e.g.) cost and convenience.

Roger Miller
soujourning under warm and sunny skies in the Denver area.