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Re: measuring calcium and magnesium

>Date: Thu, 09 Jul 1998 02:55:04 -0700
>From: Steve Pushak <teban at powersonic_bc.ca
>The issue IS:
>"what units should test kits use?"   

From a chemistry standpoint, test kits tend to use the units that are achievable 
via the chemical techniques that are available for that factor.  

From an economics standpoint, test kits tend to use the units that are 
achievable as economically as possible. 

From an R&D standpoint, test kits tend to use the units that standard test 
techiques have used and thus don't require much R&D.

From a marketing standpoint, test kit design tends to favor the needs of the 
most lucrative market segment. 

IMHO, major test kit manufacturers (LaMotte, Hach, Merck, Hanna) don't much care 
about what a few dozen aquatic plant enthusiasts think they need, especially 
since the test kits they already sell satisfy those needs with a small amount of 
arithmetic on the part of the user. Could I see a show of hands how many of us 
would plunk down, say, $75 for a test kit that directly returned results in ppm 
for Ca++ and Mg++?  I've got the fingers of my right hand ready to tabulate the 

Specialty test kit manufacturers (like Red Sea, Wardley's, Tetra, etc) will more 
than likely subcontract test kit design to the larger folks who have the 
manufacturing facilities and they will more than likely ask for a "cheap" 
version. I don't see them asking for a hideously expensive custom version 
returning results in units we think is best for us.  

As a consequence of this, the whole idea of discussing what units test kits 
should use falls in the category of how many angels can dance on the head of a 
pin.  We don't have much market clout. IMHO.
>and secondarily
>"what units are relevant for discussion of plant nutrient requirements
>and CO2?"

I would suggest "whatever units are used in the test kits that the majority of 
us use and trust."

>PS My sincere apologies for mentioning the dreaded H-word again. ;-)

Uh-huh :-]

George Booth in Ft. Collins, Colorado
 Do you want to know how I did it?