substracting nitrite test results from nitrate test results

Azedenkae

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Hey guys,

So for nitrate tests like API's, it converts nitrate to nitrite before reading it.

Now, if I want to substract my nitrite results from nitrate results to get a more exact number, would it be as simple as multiplying the nitrite results by 1.3478 (or whatever the ratio is) and substract that from the nitrate results? Of course understanding that this is not 100% precise because both nitrite and nitrate tests may not even be accurate in the first place?

Or am I missing something. :3
 
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brandon429

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Randy could this be a time where the cycling chart might be a useful reference, closest documentation we have to expected nitrite at controlled levels/not interfering= 25 ~ days on most charts?

those charts haven't been necessarily pinpointed down to reefs yet, perhaps freshwater but they haven't been excluded either. can his nitrate reading be expected to be decently baselined at 30 days after setup/especially on clean water in the new tank/low to no accumulations or shared respiration across the system yet

surely by then his initial low nitrate read w be low, and then with some bioload and waste slowly following the chart up given no natural reduction methods or plant uptakes. most dry rock starts are uptake sterile.

my questions is not so we can substract the nitrite, just to see if its interference window has passed to get a decent nitrate reading hopefully
 
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Azedenkae

Azedenkae

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No. With some kits, 0.1 ppm nitrate will read as 10 ppm nitrate, because only a small fraction of the nitrate is converted to nitrite before analysis. Then the kit multiplies it back up.
Thanks. Any ideas what fraction specifically (and why)?
 

Randy Holmes-Farley

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Thanks. Any ideas what fraction specifically (and why)?

With Tropic Marin it is 100:1. So 0.1 ppm nitrite means 10 ppm nitrate false reading.

Salifert is also high, and may be identical, but I'm not sure. Habib Sekha (owner of Salifert) never said, only that it was high and that most nitrate kits did this.

Perhaps they all follow the same basic recipe, but they may vary in the fraction consumed based on times and reagent concentrations.

I am not certain why they are designed this way, expect perhaps to lower the need for the reducing agent (converts nitrate into nitrite) 100x. That reducing agent is often toxic, and reducing the level might be to avoid regulations, human toxicity, for cost, or for some other reason I do not know.
 
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Randy Holmes-Farley

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Randy could this be a time where the cycling chart might be a useful reference, closest documentation we have to expected nitrite at controlled levels/not interfering= 25 ~ days on most charts?

those charts haven't been necessarily pinpointed down to reefs yet, perhaps freshwater but they haven't been excluded either. can his nitrate reading be expected to be decently baselined at 30 days after setup/especially on clean water in the new tank/low to no accumulations or shared respiration across the system yet

surely by then his initial low nitrate read w be low, and then with some bioload and waste slowly following the chart up given no natural reduction methods or plant uptakes. most dry rock starts are uptake sterile.

my questions is not so we can substract the nitrite, just to see if its interference window has passed to get a decent nitrate reading hopefully

I expect one is stuck doing a nitrite test if one wants to be sure there is no nitrite interference in a nitrate reading.
 
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Azedenkae

Azedenkae

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With Tropic Marin it is 100:1. So 0.1 ppm nitrite means 10 ppm nitrate false reading.

Salifert is also high, and may be identical, but I'm not sure. Habib Sekha (owner of Salifert) never said, only that it was high and that most nitrate kits did this.

Perhaps they all follow the same basic recipe, but they may vary in the fraction consumed based on times and reagent concentrations.

I am not certain why they are designed this way, expect perhaps to lower the need for the reducing agent (converts nitrate into nitrite) 100x. That reducing agent is often toxic, and reducing the level might be to avoid regulations, human toxicity, for cost, or for some other reason I do not know.
I see, thanks. Any idea about the API nitrate test and what fraction of nitrate is converted to nitrite for that?
 

Dan_P

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I see, thanks. Any idea about the API nitrate test and what fraction of nitrate is converted to nitrite for that?
I did not look at API. Here are the conversions for Red Sea and the Hanna Marine Nitrate test.
 
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Azedenkae

Azedenkae

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That's not how this works at all. No one has ever done that. Not even the author of this forum.
Doesn't seem like a difficult thing to do though once one knows the conversion. I mean in most cases it probably is not a necessary thing to do, but still good to know it can be done if one really wants to do it.
 

Randy Holmes-Farley

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Doesn't seem like a difficult thing to do though once one knows the conversion. I mean in most cases it probably is not a necessary thing to do, but still good to know it can be done if one really wants to do it.

Yes.
 

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I'm interested in your motivation for this thread. Are you impatiently waiting for the cycle to finish on a new tank or do you regularly have Nitrite in tank that's been running for a while? Or maybe your just curious and conducting experiments. :)
 

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All tank that i have measured for nitrite - even mature ones have a small fraction of nitrite in them - between 0,01 -all the way up to 0.1 ppm, If you measure 10 ppm Nitrate with a test that have the 1:100 conversion a nitrite level of 0.1 will stand for all 10 ppm read nitrate!!!

Sincerely Lasse
 
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Azedenkae

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I'm interested in your motivation for this thread. Are you impatiently waiting for the cycle to finish on a new tank or do you regularly have Nitrite in tank that's been running for a while? Or maybe your just curious and conducting experiments. :)
Curious and conducting experiments. And also helping others out, especially on Reddit. If I see they measure some nitrite and a lot of nitrate, I kinda want to offer them more precise help.
 
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schuby

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All tank that i have measured for nitrite - even mature ones have a small fraction of nitrite in them - between 0,01 -all the way up to 0.1 ppm, If you measure 10 ppm Nitrate with a test that have the 1:100 conversion a nitrite level of 0.1 will stand for all 10 ppm read nitrate!!!

Sincerely Lasse
In reality, does 0.1ppm of nitrite get converted to 10 ppm of nitrate by bacteria? Seems like a lot to me, but I've no real idea.
 

Randy Holmes-Farley

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In reality, does 0.1ppm of nitrite get converted to 10 ppm of nitrate by bacteria? Seems like a lot to me, but I've no real idea.

No. It converts to about 0.1 ppm nitrate too.
 
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