Need help with Nitrate testing

Hello

As being new to fish hobby, I am a bit confused with getting Nitrate readings from a tank that we got as a present.

I did a bit of research, and correct me if I am wrong, but there seems to be two methods to present the Nitrate ppm of a sample:

• Total Nitrogen
• Nitrate-Nitrogen

Total Nitrogen seems to actually also take into account other N- species, like ammonia and nitrites, whilst Nitrate Nitrogen specifically looks and -NO3 species.

From the above, it means that Total Nitrogen will have a bigger ppm value than Nitrate-Nitrogen. From sources, it seems that the factor difference between the two is about 4.4. For example, 10 ppm Nitrate-Nitrogen would be 44 ppm Nitrate Total Nitrogen. Also, for drinking water quality, the standard seems to be max 10 ppm Nitrate-Nitrogen or 40 ppm Nitrate Total Nitrogen.

Rand Water quality tests does Nitrate-Nitrogen test for their nitrate tests.

http://www.reservoir.co.za/municipalities/govanmbeki/GovanMbeki_Dec2016.pdf

Ok, so I have a few questions:

1) On sites that talk about the maximum ppm of Nitrate in your tank, I assume they are talking about the Total Nitrogen value. For instance, I see from many sources that for freshwater the max Nitrates can be 50 ppm, but preferable under 25 ppm. For Nitrate-Nitrogen, this would be about 11.4 and 5.7 ppm respectably.
2) I bought a Salifest Nitrate test kit, which tests for Total Nitrogen - I assume this test kit can be used for freshwater tanks?
3) When I test my tap water (from Rand Water - see link above) the colour chart indicates that my Nitrate (Total Nitrogen) is around 10 ppm, which would mean that for Nitrate-nitrogen it would be equivalent of about 2.3 ppm.

However, from the above lab testing report, the max Nitrate-nitrogen reading that they got was 0.73 ppm (or 3.2 ppm Total Nitrogen). Even adding the ammonia and Nitrite max ppms, you would only get to about 1.34 ppm. and this is lab tests, so I assume my Salifest test kit is a bit out, or there are other Nitrogen species present which influences the reading.

Thoughts, or am I over analyzing things here?

 

Yes, you need a nitrate test kit for freshwater, nitrates should be kept below 20ppm, preferably around 10 ppm.
For ammonia get an ammonia test kit and for nitrites a nitrate test kit, both ammonia and nitrites are toxic to fish, keep them at 0.
There are plenty articles on cycling tanks and how ammonia turns to nitrite and then nitrate.

 

Hi Jwh

Thanks for the info, but I already know this (and doesn't answer my questions above).

So, when you say 20 ppm Nitrate, is it 20 ppm Nitrate-Total Nitrogen, or Nitrate-nitrogen (big difference in values)?

Does Salifert Nitrate test kit work for freshwater (I assume so) ?

 

AFAIK the Salifert test kits are saltwater test kits, SERA, Tetra, API, etc all make freshwater kits, and these kits measure it as Nitrate, (nitrate-nitrogen from my understanding)

 

Thanks Jwh

Crap, then I bought the wrong test kit

Will see if I can get another one and see what the results are (although, API is also Total Nitrogen).

 

Tropical fish-keeping is so much easier than Marine, that even our test kits are simpler to operate.
When it tests for Nitrate, it tests just for that, and none of the other fancy stuff that have Marine tanks have to test for.