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Re: More water hardness (long & boring)
Hi Roger,
From your last post on the subject of water hardness (APD V3 #329) I see
that we agree on several things. For instance we agree that the
commercial "carbonate hardness" kits actually measure alkalinity; that
the use of "carbonate hardness" to describe alkalinity should be
avoided; that "hardness" always refers to concentrations of various
calcium and magnesium species and not other parameters.
We seem to hold different views on whether "temporary hardness" is the
same as "carbonate hardness" (in the true sense of the word) and whether
"temporary hardness" is of any use for aquarists.
You searched the literature without finding a confirmation of the
identity of temporary hardness = carbonate hardness.I am really not
surprised, because you probably searched only the relatively recent
handbooks. One has to go to books from before the war (WW II, that is)
to find it. In the mainstream technical/scientific literature these
terms went out of use just after the war, when analytical chemistry
started turning instrumental. There was no need for them anymore! This
is exactly why I presented a *historical* overview. In my *opinion* a
historical perspective offers a clearer view of nomenclatural and
technical origins.
I don't think that these days there are many commercial analytical
laboratories using such manual analyses. Most, if not all, do it by
means of ICP or AA and ion chromatography. It is only the hobbyists that
still do it by hand, but even here each year there appear more and more
electronic analytical gadgets designed for the hobbyist. They are
covenient to use and are slowly displacing the chemical kits.
Unfortunately, currently I do not have a convenient access to a good
university library to look things up in order to give you an
authoritative "chapter and verse" that temporary hardness = carbonate
hardness. If I remember correctly (and that's an IF), in the old "Bible"
- Analysis of Waters and Wastewaters, published by AWWA with other
interested Societies - and here one must find an old copy, with, I
think, a red cover (not blue or the present green) is just such a
description. There they also describe the "soap foam" method of
determining water hardness, relly ancient stuff.
While water hardness was "mainstream science", aquarists did not worry
(or know) about it. "The Aquarium Book" by E.G. Boulenger (THE
Boulenger!), published in 1925, does not even mention water hardness! I
think that water chemistry for aquarists became fashionable only after
WW II. The "Handbook of Tropical Aquarium Fishes" by H.R. Axelrod and
L.P Schultz, published by McGraw-Hill in 1955, has about 1/2 of a page
on hardness, recommending the soap-suds method, even providing an
address where to buy the soap.
You say:
> Certainly if we were to accept Mr. Slusarczuk's definition of > carbonate hardness=temporary hardness, then it would not be the > same as alkalinity. My tap water, for instance has 2 degrees of > temporary hardness, but 7 degrees of alkalinity. If I mix a > solution of sodium bicarbonate and test it, I find no temporary > hardness, but plenty of alkalinity.
I am not certain HOW you measured temporary hardness (sensu stricto),
but I agree with you, that it is not the same as alkalinity - that's
EXACTLY my point!. As to the semantic identity of carbonate hardness =
temporary hardness, let's look at it from another angle:
There should be (is?) general agreement, that water hardness can be
divided into PERMANENT and TEMPORARY hardness. There should also be no
argument, that boiling the water will precipitate Ca/Mg carbonates i.e.
the *temporary* hardness. It does not take much of a logical leap, that
if temporary hardness is comprised of the Ca/Mg CARBONATES, it IS
"carbonate hardness"! In the "good old days" alkali and alkaline earth
carbonates could most conveniently be quantitated by titration with an
acid - an identical procedure to ALKALINITY determination. It is not
difficult to perceive how the two terms were synonymized in the popular
aquarium literature and in the minds of aquarists. That, however, does
not make "carbonate hardness" & "alkalinity" identical.
For lack of a better source in my personal library, I quote from
"Aquarium Water Chemistry" by Dr. R. Geisler and published by TFH
(1963), page 6: - "By hardness we mean the content of dissolved calcium
and magnesium in the water. Depending how much calcium and magnesium is
tied in with carbon dioxide or other acids, we speak of carbonate
hardness and residual hardness, both of which combine to give us total
hardness."
A more recent book "Aquarium Plants" by Barry James, published by
Salamander Books Ltd. (1986) on p. 14 states: "Since the carbonates
produced can be easily broken down by boiling, this type of hardness is
called temporary hardness or carbonate hardness".
>
> As aquarists we really have no particular interest in temporary > hardness, but we do have a substantial interest in alkalinity. > Temporary hardness just gives us a breakdown of total hardness > and for our purposes I think we only need to know about total > hardness. (snip)
Because temporary=carbonate hardness CONTRIBUTES to *alkalinity*, but
alkalinity, aside from the Ca/Mg carbonate contribution, has NO formal
contributory relationship to hardness, it would seem to me that some
attention should be paid to it, if one minds alkalinity at all.
(snip)
> Temporary hardness has no inherent relation to buffer capacity. > An alkalinity test is an excellent measure of bicarbonate in > most unpolluted natural waters.
I agree with the second statement, but disagree with the first: In most
"natural" waters temporary=carbonate hardness IS the *buffering
component* of Total Hardness! It's the famous carbonate/bicarbonate
equilibrium equation that describes the buffering capacity of natural
waters. That does NOT mean that other species do not contribute to
alkalinity, because they do!
(snip)
> My view on these definitions: simplify, simplify, simplify
> "carbonate hardness", when used in the hobby refers to > alkalinity. Otherwise it appears to be a meaningless term and > should be avoided. If there is an accepted definition that > equates carbonate hardness with temporary hardness then this > only emphasizes our need to avoid using the term.
I could not agree more for the need of simplification. As the popular
saying goes "I agree one thousand percent"! Then why do some people
insist on using "carbonate hardness" when they mean "alkalinity"?
Because of "tradition"? "Simplicity?"
I do not think that any member of this list has NOT heard, or does not
understand, the term "alkalinity" (certainly not after THIS discussion)
so, why not decide to use "alkalinity" instead of "carbonate hardness",
never mind whether they are identical or not!
I realize, that for most members of this list this discussion on the
finer points of water hardness is not that interesting. In that spirit I
have decided not to post any more "wisdom" on this topic on the list.
Anybody who has further questions/views/ arguments is invited to contact
me directly at <yurko at warwick_net>
I thank the many who posted or e-mailed their support.
Best,
George "S"
(The "S" is so that there can't be any confusion with another George on
this list. He is totally blameless for my views!)