Nitrate test kits

["Eric Wahlig" <ewahlig at earthlink_net>]

Roy was commenting/asking about nitrate test kits. I don't know for sure if
they are available in your area but I suspect so as they have a European
division in Dusseldorf, Germany for customers in Europe, the Middle East,
and Mediterranean Africa. The European division can be reached at:
<Infohach at drlange_de>.

I have the Hach Nitrate kit Model NI-11(Cat. No. 1468-03). This kit is one
of their high range nitrate kits; measures 0-50 mg/L by 1mg/L increments.
However, the 1mg/L increment is for measuring *nitrate nitrogen* and the
directions say "Note: Multiply the mg/L nitrate nitrogen value by 4.4 to
obtain the mg/L nitrate." So, in essence, the 1mg/L increment is now a 4.4
mg/L increment if you are testing for nitrate. Since, in a planted tank, we
are aiming to keep a small surplus of nitrate available in the water column
(values of more than zero but less than over abundance) then this kit, at
least for me, is not precise enough. If you are looking to test nitrate in
the range of 0 -10 mg/L then I would recommend the NI-14 which has two
ranges. One range is 0-1 mg/L by 0.02 increments and the other range is
0-10 mg/L by 0.2 increments. You get approximately 50 tests. Of course, I
am not a Hach representative so you should probably check with them to be
sure this is what you want before spending the $53 USD. They make several
nitrate test kits; I think 10 or 11 different models ranging from test
strips (about $15 USD) to Colorimeter (about $310 USD).

Regarding the comments about the discrepancy between the measurements:
About a year ago I spoke with a Hach field rep and he said that the
particular kit I had was subject to error induced by the characteristics of
the tester. That is to say, the test results were variable to a significant
degree by interpretation of the instructions by the tester. The
instructions say add the reagent, cap the test tube, and shake vigorously
for exactly one minute. Well, how vigorous is vigorous and from what point
in the process do you start the "exactly one minute" count as it takes a
few seconds to empty the reagent packet into the test tube and cap the tube
before you can shake it. I never got a verification from him about the
effects of my interpretation and testing procedure because I didn't have
the test kit with me when I saw him and I wasn't about to pay for a house
call.  I have not read the article in the UK magazine _Practical
Fishkeeping_ that Roy alludes to but this may be the reason for the
discrepancy mentioned; I'll read it if I can find it. Roy, can you
elaborate on the article?
 
--- Eric