Ammonia - Nitrite - Nitrate

[Skavatar]

Zka17

from our previous discussion on the Nitrite thread. Help - Nitrites Wont Go Down?


Ammonia ppm = Nitrate ppm?

Post #8

When the test kits give measurements in ppm, this refers to mg/L.

Comparing an equal number of molecules of ammonia to nitrite to nitrate would be equal if you are considering molarity, but not when you put mass into the picture.

Molecular weights:
N = 14.01
0 = 16.00
H = 1.01

NH3 = 16.03
NO2 = 46.01
NO3 = 62.01

You still have the same number of nitrogen atoms, but the molecule has "gained weight" because of what it has been converted to.

 

[Skavatar]

ppm (parts per million) as a measurement unit is pretty controversial - at least in my head... as a scientist, I am working with SI units (ppm is not SI), and just cannot take it as it is... The controversy comes from the possible definitions: ppm could be a mass fraction (kg/kg), or a mole fraction (mol/mol), or a volume fraction (m3/m3 or l/l) - now, mg/l is none of these, except if we are talking about water (H2O)...

Most of the scientific studies I've read and discussed on here about fish, and water quality issues all use ppm or mg/L. Even our city's annual drinking water report uses ppm, ppt, ppq, and mg/L. Since fish live in water H2O, we use ppm and mg/L.(my best guess)

Do we know if the test kits used by us are meaning that ppm=mg/l?

according to API instruction manual, yes ppm=mg/L

An another question is what exactly our test kits are measuring? Ammonia-nitrogen and nitrite-nitrogen (the nitrogen derived from ammonia/nitrite)? Or effectively the ammonia and nitrite? Because if they measure the nitrogen derived from each, then 1 ppm ammonia = 1ppm nitrite...

I believe the API test tests for total weight, ammonia/ammonium(NH3/NH4+), nitrite (NO2), and nitrate(NO3), and not the -Nitrogen only weight.

Also the EPA standard in drinking water is no more than 10ppm NO3-N which is about 44ppm nitrate. Probably why most fishkeepers say to keep nitrate levels less than 40ppm.

My logic is: one molecule of ammonia transforms into one molecule of nitrite - why would we use a measurement unit which shows that during this transformation the end product is triple of the start product? Why would we take in consideration that the molecule gained weight when we are looking for the number of molecules?!

I guess that's just the way the industry has done it for decades. Maybe the way the tests are, its just easier to use ppm for hobbyist, since most of us aren't engineers, to calculate the actual molecules.

misc info I found informative.

When dissolved in surface water, ammonia exists in two forms: NH30 (unionized) and NH4+(ionized). Ionized ammonia does not easily cross fish gills and is less bioavailable than the unionized form (Francis-Floyd 2009; EPA 1989). The unionized form (NH30) can cross from water into fish, and once inside, some converts to the ionized form (NH4+), which then causes cellular damage (EPA 1989). The primary form of total body ammonia in fish at physiological pH (7.0–8.0) is ammonium, or NH4+; it is this chemical species that is responsible for toxic effects (NH30 is the most toxic form to aquatic life, but NH4+5 BMPs focused on the use of insoluble blasting agents and good housekeeping practices (USFS 2004). is the most toxic form in the body)
A Literature Review of the Threat Posed by Ammonia to Fisheries from Mining in the Bristol Bay Basin4 (McKenzie et al. 2008; Smart 1976; Hillaby and Randall 1979). Although unionized ammonia is the more toxic form, toxicity is most commonly expressed as total ammonia - the sum of NH30 and NH4+ in water.
page 3

Nitrite/Nitrate cause Methemoglobin by stealing electrons. Nitrite/Nitrate oxidizes the iron Fe2+ in hemoglobin by stealing an electron and prevents it from transporting O2 to organs/tissue.

 

[Coptapia]

I’m not sure what this thread is trying to say .... (?)

 

[Skavatar]

I’m not sure what this thread is trying to say .... (?)

it was a side discussion from the thread I linked, did not want to derail that thread.

 

[Guppygirl88]

I’m not sure what this thread is trying to say .... (?)

They are having a contest - to see who can "think" the farthest

 

[Coptapia]

it was a side discussion from the thread I linked, did not want to derail that thread.

So what is this one about... ?

Edit....Tried to delete this post but it won’t let me. I suppose if I can’t tell what it’s about I don’t deserve to know?

 

[Zka17]

Skavatar - thank you very much for opening this thread! I was feeling bad in the other one...

I am completely aware of the biological effects of the ammonia/nitrite/nitrate - just thrust me on that , but thanks for the literature!

I did miss the ppm = mg/l thing on the API instructions, I was looking more to find what method of detection they are using... Although I am not sure on that, I did found test which are knowingly working on the base of nitrogen amounts (ammonia-N, nitrogen-N) - and those described pretty detailed the reactions. Now, I am thinking that it would be an interesting experiment to compare the API kit with those... like this one:

and this:

 

[Skavatar]

it would be interesting to see the difference, but expensive.

I only found a few aquarium related discussions on Lamotte, they say it is very accurate, but also very expensive for most hobbyist fish keepers.

Dr Novak says Lamotte is used by professionals (professors, scientists, etc) its a 10. API is a 1.

 

[Zka17]

I think I am going for it... just ammonia and nitrite... - nitrate is not important to me, doing water changes anyway...

 

[Zka17]

I have received my LaMotte Ammonia-Nitrogen and Nitrite-Nitrogen kits!

My quarantine tank is still cycling (I never had a tank cycling so long!) - so I do have ammonia, and finally nitrites too...

Just a reminder: the goal of this experiment is to figure out what exactly the API Master Freshwater kit is measuring at the "Ammonia" and "Nitrite" tests...

This is important to decide if 1 ppm NH3 = 1 ppm NO2 or 1 ppm NH3 = 3 ppm NO2... - if the API kit is measuring ammonia/nitrite nitrogen, then it is on-to-one (since there is one nitrogen atom in both molecules)

Unfortunately, I have to start with the nitrite test, as my ammonia is too high for the LaMotte test - it has the max value of 3 ppm, but the scale is in smaller increments. Will get back to this one!

As I already mentioned, nitrites just showed up in my tank... The API test developed a color which indicates a value between 0 ppm and 0.25 ppm (a very gentle, but certain purple). The LaMotte developed a color between the values of 0.1 ppm and 0.2 ppm. Again, the LaMotte is measuring nitrite nitrogen (NO2-N)... to get the real nitrite value, the NO2-N value needs to be multiplied by 3.3 (as per the manufacturer's instructions) - so I do have nitrites (NO2) somewhere between 0.33 ppm and 0.66 ppm...

So, it is kinda hard to exactly figure out the values of both tests, although the LaMotte gives a more precise interval. But, API's 0-0.25 ppm is way much closer to to LaMotte's 0.1-0.2 ppm NO2-N, than the 0.33-0.66 ppm NO2.

Overall, I would say that API is actually measuring the nitrite-nitrogen, and not the nitrite itself... I did 3-3 tests only one day (the concentrations in the tank haven't changed), but I will keep testing to see if this trend stays the same...

Ammonia test comparison is coming up soon!

 

[Skavatar]

good info.

instead of waiting for the ammonia to drop naturally, you can do a dilution. half tank water and half tap water.

 

[Zka17]

Good idea! Tonight I will try that... it is also time for a water change too, so I can measure both ways - before and after, and dilution method...