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Re: Nitrates and testing
> From: "Leslie S Keys" <DAVIDB26 at prodigy_net>
> Subject: Nitrates and testing (question)
> I seem to have a bit of an anomaly as far as my Hach nitrate test kit is
> concerned. I have been adding KNO3 (in the form on saltpeter) at the rate
> of ¼ tsp. for the last 2 days. I calculated that the concentration - if the
> plants used none - should be at about 6ppm. However, after the first
> addition the Hach test kit shows concentration as .25 Nitrate nitrogen = 1.1
> PPM Nitrate.
> After the second dose the test showed .35 = 1.5 PPM Nitrate in other words I
> appear to be missing 4.5 PPM NO3. Previously to the KNO3 addition the kit
> read zero nitrates.
Did you calibrate the test kit with a solution of known concentration?
It's one of the first things I do with a new kit.
> The test kit is not accurate (or could be I am not performing the test
You are looking at quite low concentrations - is it really possible
to distinguish the colours well enough to get that accuracy?
> The calculations are incorrect - I will put my assumptions later
> The plants are eating most of the NO3 / the green water algae have eaten
> most of the NO3
It can disappear pretty quickly.
> The fluorite substrate has somehow sequestered the NO3 (wild speculation).
Nitrate is pretty difficult to sequester.
> Saltpeter is not just KNO3
It should be.
> 75 gallon
288 litres, say 250 L of water.
2.4g of KNO3 at 61% is about 1.46 g of NO3, so about 6 ppm, O.K..
Paul Sears Ottawa, Canada