Pet Forum / Aquaria / Marine Reef / June 2004

"HI 93752 measures calcium concentration from 0 to 400 mg/L and magnesium from 0 to 150 mg/L"

Will you dilute sample 1:1 to get into the range for Calcium and 1:10 to get in range for Magnesium?

Will it work in saltwater at all? From the description I get it is designed for freshwater....

Interesting meters, but lets wait for Boomer :-)

Marc & Pszemol

It MAYBE OK. This test does not follow the same rules for NaCl interference, like the
other ones we discussed, NO3, NO2 . HACH and La Motte do not make a spectro that goes this
high. Matter of fact, they do not even make a small hand held like these to measure Ca or
Mg at all. They limit theirs to only a few mg / l and that is on the really big spectro's.
I don't see any ions one needs to be worried about that would interfere. Obviously, it may
not do to well for Mg. There is the dilution factor but a dilution factor of 10-1 is
pushing it waaayyy .............to much. I will call them tomorrow for a talk :-) As I
tried to convey before . Some of these units can and will work in seawater quite well, as
there are no ion inferences to worry about, such as Phosphate, Si and Cu. and even DO. It
is an interesting toy :-) The PDF on it does say "in water and wastewater" no mention of
seawater.

Ok another L@@K at the PDF guys. Sorry, it is a no go :-(

Testing for Ca

Interferences;
..............................................concentration .........reading
Acidity (as CaCO3) above .....1000 mg/L ...........lower.............OK
Alkalinity (as CaCO3) above ..1000 mg/L ...........higher.............OK
Magnesium (Mg2+) above ......400 mg/L............. higher.............Seawater is 3 times
this

Testing for Mg

Interferences:
.............................................concentration ..........reading
Acidity (as CaCO3) above .....1000 mg/L............ lower.........OK
Alkalinity (as CaCO3) above ...1000 mg/L.......... higher.........Ok
Calcium (Ca2+) above .............200 mg/L ............higher........Seawater is 2 times
this

So what does this say ? If you are testing for Ca the Mg in seawater is way to high.  If
you are testing for Mg the Ca in seawater is way to high.