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Re: equivalents

Just a follow up note here as it has been pointed out that my 
discussion of equivalents neglected to mention that when we are 
discussing cations like calcium and magnesium the convention is to 
take into account the charge number when discussing concentration of 
these ions. Calcium has a +2 charge so 1 equivalent of calcium ions 
is the same as 2 equivalents of positive charge. By convention 
hardness is discussed in terms of the amount of positive charge 
contributed by both magnesium and calcium. Magnesium contributes 1 
positive charge and calcium 2 for each individual ion of the 
respective elements. So by convention the hardness figures also take 
into account the charge contribution. So in my example in the first 
post, 40 mg/L of calcium is equal to 1 meq/L of calcium ions, but 
equal to 2 meq/L of positive charge/general hardness.

-Greg Morin

Gregory Morin, Ph.D.  ~~~~~~~Research Director~~~~~~~~~~~~~~
Seachem Laboratories, Inc.      www.seachem.com     888-SEACHEM