RE: Definition of alkalinity

["Yvan Alleau" <yalleau@coas.oregonstate.edu>]

Hi Steve,
As both a chemist and oceanographer, I agree with you when you say that the
concept of alkalinity has been twisted quite a bit and in many wrong ways.
My memory is fuzzy now about the details (I do remember that it was
complicated though!) but I would encourage you to go to the library and look
for a book titled "Principles and applications of aquatic chemistry" by
Francois M. M. Morel and Janet G. Hering (Wiley Interscience Publication.
ISBN 0-471-54896-0).
Look at chapter 2 "Alkalinity and related concepts" : you should find what
you are looking for.
The book has many other great info also...for those of you who like
chemistry.
If you can't get the book, let me know and I will copy the pages and send
them to you.
Have a great Friday!


Yvan Alleau
Oregon State University
College of Oceanic and Atmospheric Sciences/
Hatfield Marine Science Center
2030 SE Marine Science Drive
Newport, OR 97365
1-541-867-0206
-----Original Message-----
From: owner-apisto@v2.listbox.com [mailto:owner-apisto@v2.listbox.com] On
Behalf Of Stephen.Weir@csiro.au
Sent: Wednesday, April 14, 2004 10:39 PM
To: apisto@v2.listbox.com; aquaria@yahoogroups.com
Subject: Definition of alkalinity

Dear all,

This is probably not of specific interest to apisto fanciers, but is a more
general aquaria topic.  I do however know there are a few chemistry
competent keepers on these lists.

As a bit of background, I'm reviewing an information sheet on water
chemistry for ponds and the author wishes to use the term alkalinity.  To me
as a chemist alkalinity is the opposite of acidity, and so implies an excess
of hydroxide ions in solution.  The OED defines it as "the quality of being
alkaline; alkaline character or property".

However I know that in dumbing things down many aquarium book authors have
twisted the meaning to indirectly represent carbonate hardness, since the
overwhelming majority of alkalinity in natural waters is due to
carbonate/bicarbonate.  They then twist it a bit more, since
carbonate/bicarbonate is also the buffering system in natural water, and
alkalinity then becomes equivalent to buffering capacity.  The definition of
alkalinity most often suggested by these authors is "the resistance to pH
change upon addition of an acid", which is a long way from what I take
alkalinity to mean.  They even quote alkalinity in terms of degrees or ppm,
which I know refers to CaCO3, and is alkaline, but it still irks me.

What I'd like is for anyone that can find a definition of "alkalinity"
related to aquaria to please let me know of it.  If the author of the
information sheet I'm reviewing insists on using the term I at least want to
have an accepted definition I can quote and reference.  Or if anybody can
propose a different set of definitions that are familiar yet accurate I'm
all eyes :)  

FWIW, I checked the krib but the main article on carbonate hardness (by
Larry Frank) actually has several errors in it.

Thanks in advance to everyone,

Steve    

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