# Help understanding NT Labs liquid ammonia test



## Edward Shave (13 Sep 2021)

NT Labs say their ammonia test results are expressed as nitrogen content rather than concentration of ion. If I want the concentration of ion I have to multiply by 1.12.
I am plugging the test result into the free ammonia calculator I found here.
My question is... What type of result is the free ammonia calculator expecting? Do I need to multiply by 1.12?


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## dw1305 (13 Sep 2021)

Hi all,


Edward Shave said:


> NT Labs say their ammonia test results are expressed as nitrogen content rather than concentration of ion. If I want the concentration of ion I have to multiply by 1.12.


I assume it is just nitrogen content of NH3, although it should be 1.21, rather 1.12?

It is worked out from the RAM of nitrogen (N) = 14 and hydrogen (H) = 1, so the RMM of NH3 = (14 + 3) = 17 and  14/17 = 1.214.  (NH4+ would be "_multiply by 1.29_").   These tests usually add an acid to convert all the TAN to ammonium (NH4+), because dissolved gases are problematic to measure. If it adds a base (usually NaOH) it will convert all the NH4+ to NH3.


Edward Shave said:


> I am plugging the test result into the free ammonia calculator I found <"here">.


This does something slightly different from the way you want to use it, it tells you *what proportion of the Total Ammoniacal Nitrogen (TAN) is as dissolved ammonia gas (NH3). *It should give you the same result as the table below.

TAN comprises NH3 ("un-ionized" and toxic to aquatic life) and the ammonium (NH4+) ion ("ionized" and relatively benign). The proportion of the TAN that is ionized or un-ionized is <"*dependent upon temperature and pH*">*.  




*



cheers Darrel


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## Edward Shave (13 Sep 2021)

Hi Darrel, many thanks for your detailed reply. I got  the 1.12 figure from this article. However if I was a betting man and going by past experience I'd put my money on you being right. LOL

I get that there is total ammonia and free ammonia (which I think is NH3?) but as usual with chemistry they can never leave it at that...! There are always If's & but's LOL.
Given that we can get the percentage from your chart (in my case 0.5%) I'm still unsure of which number to plug in to get the actual concentration of NH3. In other words do I need to multiply by 1.21 or not?


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## MichaelJ (13 Sep 2021)

FYI Here is another free ammonia (NH3) calculator. (gives the same results as above table btw.  i.e. free_ammonia = table1(temp,pH) / 100 x total_ammonia  )


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## Edward Shave (13 Sep 2021)

MichaelJ said:


> FYI Here is another free ammonia (NH3) calculator. (gives the same results as above table btw.  i.e. free_ammonia = table1(temp,pH) / 100 x total_ammonia  )


Thanks for that. This helped in as much as it precisely specified exactly what to enter as the total ammonia value. i.e. 
"Total (NH3+NH4)-Nitrogen Concentration (mg/L)"
As near as I can figure (as a non chemist) that is the same form as returned by my NT Labs test.
If anyone knows better please let me know...


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## dw1305 (13 Sep 2021)

Hi all,


Edward Shave said:


> I got the 1.12 figure from this article. However if I was a betting man and going by past experience I'd put my money on you being right.


You would have got your money, it should be 1.21.


Edward Shave said:


> I get that there is total ammonia and free ammonia (which I think is NH3?) but as usual with chemistry they can never leave it at that...!


That is right, free ammonia = NH3.  To take pH and temperature out of the equation scientists use "Total Ammoniacal Nitrogen" (TAN). I think TAN helps as a concept.

Some aquarists will argue that you can ignore NH4+, because it isn't toxic, but I look at a bit like the relationship between kinetic (~ NH3) and potential energy (~NH4+) when you have a large mass on an inclined plane. It might not be a problem, but if the mass starts moving it is going to make a hell of a mess. Same with  free ammonia (NH3), if you end up with a lot of it, it is going to be total "wipe-out".

The real answer is to get rid of the TAN <"as rapidly as possible"> and have systems with built in capacity to deal with <"rogue large masses">.


Edward Shave said:


> This helped in as much as it precisely specified exactly what to enter as the total ammonia value. i.e.
> "Total (NH3+NH4)-Nitrogen Concentration (mg/L)"
> As near as I can figure (as a non chemist) that is the same form as returned by my NT Labs test.


It is.

cheers Darrel


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