Nitrate-Nitrogen or Total Nitrate

[johnkristie]

Some nitrate kits measure total nitrate and others nitrate-nitrogen. Which is a better measurement of nitrate? Does it really matter? I've heard some talk about keeping nitrates below 40ppm for FO tanks. Is that for total nitrate or nitrate-nitrogen? What are the best kits to use?

[hackteck]

i use the seachem multitest marine basic

[BillyZ]

I've never heard of a "nitrate-nitrogen" test but I did some quick googling and it seems that Nitrate-Nitrogen is more for testing soil..? do you have any links to where you were seeing these kits offered?

I have always used a normal nitrate test kit (Salifert) and to the best of my knowledge, that's all i've ever heard discussed here. Hopefully if anyone here has used them and can explain the difference to us, they'll post for us

[cmor1701d]

From the LaMotte Colorimeter 1200 web site.

NITRATE-NITROGEN
TEST METHOD SPECIFICATIONS
APPLICATION
This method determines nitrate levels in drinking, surface, saline waters, domestic, and
industrial waters.
RANGE
0 - 3.0 ppm Nitrate Nitrogen (Range can be extended by dilution.)
METHOD
Powdered cadmium is used to reduce nitrate to nitrite. The nitrite that is originally
present plus reduced nitrate is determined by diazotization of sulfanilamide and nitrite
followed by coupling with N-(1 naphthyl) -ethylenediamine dihydrochloride to form a
highly colored azo dye which is measured colorimetrically.
INTERFERENCES
Nitrite interferences at all levels. Use the following equation to compensate for nitrite
interferences: Test result (ppm) - (Nitrite-N (ppm) x 5.5) = true Nitrate-N reading.Strong oxidizing and reducing substances interfere. Low results might be obtained for
samples that contain high concentrations of iron and copper.

[johnkristie]

For example, the SeaChem kit I have now measures for nitrate-nitrogen, but the Aquarium Pharmaceuticals kit I used to have, measured total nitrate. Look at the details of the instruction sheet or on the side of the box. It should say what exactly your kit measures. The reason I'm asking is that my old Aquarium Pharmaceuticals kit was reading 40 mg/L, but when I got the new SeaChem kit measuring nitrate-nitrogen, the readings immediately went down to less than 10 mg/L. And since I've always heard to keep the nitrates in the tank under 40 mg/L, I was just curious as to which measurement of nitrate that was referring to.

[artur]

Thanks for that question.Ihave the same problem.I tried to keep the parameters perfect.My aquarium Ph. kit says 20 and sachem kit 5.of nitrate.I am changing the 35 gal every 3 weeks in my 90 gal tank<corals and fish>Wich test should i trust?Everythink is doing well in tank so i guess it is 5.It is so frustraiting when i change the water and it still shows on that one test 20.I think that test is bad.Sachem shows 5 and i think that is right sinse everythink in tank looks good?im really confused.