The new Marin Nitrate LR checker

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Lasse

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I´m among those that have been very hesitant about the new HI781. This because I know how difficult it is to analyse low level of NO3 in salt water-. I had said - i believe it when I see it :D

Now I have seen it and even test it.

What do I think about it now?

I have not be able to test it according to accuracy and precision - it means I have not test it against a known good method - only compare it with other hobby tests there you need to have a good ability to interpret colors. And yes I´m a little bit impressed after my two readings :D I know of experiences that when you use a new testing methodology - the first 10 - 20 tests are like using a shotgun - bullets everywhere. these two was 2.40 and 2.47 ppm. The result is line with expected figures.

However all this types of analysis of nitrate will be affected if there is NO2 in the test sample before the test. I know that my aquarium normally run between 0.01 and 0.03 ppm. Therefore I always analyse NO2 when I analyse NO3. Problem with the Hanna checker - I can´t find the conversion factor för NO2 interference on the NO3 readings.
@Hanna Instruments can you give me that conversion factor? If it is a high factor - it will affect the result rather much

Sincerely Lasse
 
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Lasse

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I did a test now of my Nitrite concentration using Tropic Marine Pro nitrite/nitrate test. The nitrite was 0.02. Tested also the nitrate concentration with the same test. If not compensate for the nitrite concentration - the test said just a bit over 2 - I read around 2.4 mg/L. If I compensate for the nitrite concentration (0.02 mg/L) - the real result should be around 0.4 mg/L NO3. My test with Hanna HI781 give a result of 2.65 mg/L. I do not know the conversion factor for HI781 but for the TM nitrie/nitrate Pro test - it is 100. It means that if you read 0.02 mg/L nitrite - you should withdraw 2 mg/L from your nitrate readings. As you can see - if you should know what the HI781 results stand for you need to know the conversion factor - if it is 50 - my real result with 0.02 nitrite is 1.65 mg/L and if the factor is 100 - it will be 0.65 mg/L At a reading of 2,65 mg/l I would not do anything - however if the real result is 0.65 - it calls for action (dosing NO3).

For me that is more afraid of going to low compared with going to high it is critical to know the conversion factor - so please give us that.

Sincerely Lasse
 

chema

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Hi Lasse: you are absolutely rigth. Low amount of nitrites it is not big deal when you have high nitrate concentrations. But when you are testing low amounts, as it is the case with the new Hanna checker, it may represent a large difference.

I have also ordered the nitrate checker and I'm planning to buy the nitrite checker too. Knowing the conversion factor is of paramount importance when measuring concentrations in the range of the nitrate checker.
 

robbyg

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Lasse I Just used Hannas online chat to ask them the question:

They are their right now, just click on the link and then click on the round blue chat symbol at the bottom right hand side. Maybe you can explain it better than me.

https://knowledge.hannainst.com/knowledge/how-do-i-contact-your-technical-support-team

Here was the response

_____________________________________________________________________________
Hi, welcome to Hanna! If you have any questions, we're here to help!
Before we get started, what's your name?
12:31 PM

Rob
12:32 PM

Hanna Instruments, USA
Thank you Rob. Would you like to leave your email in case we get disconnected?
12:32 PM

No Thank You
12:32 PM

Hanna Instruments, USA
Our next question for you is - what state are you located in?
12:32 PM
Florida
12:32 PM

Hanna Instruments, USA
Would you like to search our knowledge base for more information, contact our technical team (repairs, returns, etc.), or chat live with one of our specialists?
12:32 PM

Talk with a Live Specialist
12:32 PM

Hanna Instruments, USA
Thanks. We’ve passed along this information. A member of our team will be in touch soon.
12:32 PM

how soon
12:33 PM

Ron Dumais
Bam! How can we help Robert?
12:35 PM

Hi you still there
12:58 PM

Rob
Yessir!
12:58 PM

I have the new HL781 meter for reading LR Nitrate. I would like to know if you have the conversion factor for the meter to NO2
12:59 PM

Ron Dumais
nitrogen dioxide?
1:00 PM

NO3 and NO2
1:00 PM

Ron Dumais
nitrate / nitrite okay
1:00 PM

Rob
Yes
1:01 PM

Ron Dumais
I mean i know we have meters for each, but I'm not too familiar with a conversion or if that type of computation works.
I would assume not otherwise everyone wouldn't have wanted the nitrate checker? haha Let me take a look for you though.
1:01 PM

Rob
Yes most testers for NO3 have a conversion factor for NO2
1:02 PM

Ron Dumais
I found a little info online, not sure how helpful - To convert from units of nitrogen (NO3-N) to nitrate (NO3), multiple the value by 4.427. To change from nitrate (NO3) to nitrogen (NO3-N), divide the value by 4.427.
1:02 PM

Rob
Let me test that out and I will get back to you. Thanks.
1:04 PM

Ron Dumais
I also found this I'm currently looking at https://www.hannainst.com/hubfs/006...HI781-Saltwater-Nitrate-LR-Rev1.pdf?hsLang=en
1:04 PM

Ron Dumais
Our aquarium expert has been out sick, but you can try emailing Kevin Costa at [email protected] as well.
1:06 PM

OK Thanks.

_______________________________________________________________________________

I don't think I got the right answer but I am not as well versed in this as you, so maybe you should try Lasse.

Rob
 
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Lasse

Lasse

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That answer just say that even if they are fast - they just not know what they are talking about. Nitrite is mentioned in their folder as an interference and they should know how much that interference is.

Sincerely Lasse
 

robbyg

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That answer just say that even if they are fast - they just not know what they are talking about. Nitrite is mentioned in their folder as an interference and they should know how much that interference is.

Sincerely Lasse
Lasse I am not very familiar with the stuff so I could not ask the question properly. You should go to the website and chat with them OR email the Chemist who deals with that meter. They gave me his email address and I posted it above.
 

chema

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Lasse, I assume that as Tropic Marin gives the conversion factor for its nitrate/nitrite test, that is your favorite for both measurements

I have never used them.
 

chema

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Robbyg: I guess that the question would be: can you quantify the interference produced by nitrite?
 
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Lasse

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Lasse, I assume that as Tropic Marin gives the conversion factor for its nitrate/nitrite test, that is your favorite for both measurements

I have never used them.
Tropic Marin have two package of NO2/NO3 tests - one normal and one that's named NO2/NO3 Pro I have both but I only use the Pro version. The normal has to low resolution for me. I have test both saliferts and Red Sea Pro NO3 tests and for me and for my eyes - the TM test is the best. That´s the one I recommend to use - the normal is not as good IMO. Both test have with a tabell for converting read NO3 - read NO2 into a real NO3 reading. Of the tabell - it is easy to see that the conversion factor for the normal test is 50 and for the Pro - it is 100. It means with the pro test - if you read 0.02 in NO2 and 3 in NO3 - the real NO3 value is 1 ppm



Robbyg: I guess that the question would be: can you quantify the interference produced by nitrite?

Yes - that´s the question and for all other test I know of - it is linear - it means there is a factor you should multiply the NO2 reading with to see which is the real NO3 value.

I have sent an email

Sincerely Lasse
 

robbyg

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I went back on line again and got a different guy. He said yes that NO2 would effect NO3 but he said that the Chemist who deals with Aquarium testers was on sick leave so he would have to email him and the get back to me. He has my email so I am hoping to get a response. He said that this had not come up before but was wondering if I could not use a Hanna Nitrite test and do the subtraction? I had no idea if there is a fixed ratio or not and neither did he. So @Lasse you can try them back in a few days or if the Chemist replies to me I will post the response.
 
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Lasse

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There is probably a fixed ratio - only problem - they have not publish that. It is not so easy that you can just take the nitrite level and subtract from the Nitrate readings- It is a multiply factor - probably between 50 and 100 before the subtraction.

Sincerely Lasse
 

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There is probably a fixed ratio - only problem - they have not publish that. It is not so easy that you can just take the nitrite level and subtract from the Nitrate readings- It is a multiply factor - probably between 50 and 100 before the subtraction.

Sincerely Lasse
Do you have this adjustment ratio for other nitrate tests like salifert?
 

robbyg

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@Lasse I got back an email reply today from Hanna and it is kind of disappointing.


I ask your question to my R&D team and was told….

The HI781 uses a chemistry in which nitrate is reduced to nitrite. The nitrite then reacts with an indicator to produce a pinkish/purple color. The intensity of the color produced is proportional to the amount of nitrite that is present. The nitrite being measured would include any nitrite present in the original water sample plus the nitrate that is reduced to nitrite.

It is not possible to differentiate nitrite in the sample from the nitrite produced by the reduction of nitrate. For this reason nitrite is listed in the instruction manual as an interfering compound.

Best Regards,
Pete Smith
Tech Service Representative
800-426-6287 ext. 134
 

robbyg

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So does this mean do a seperate Hanna Nitrite test and then do basic subtraction?
 
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Lasse

Lasse

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So does this mean do a seperate Hanna Nitrite test and then do basic subtraction?

I would say so
No not so easy. The conversion of nitrate into nitrite is time depending. it is a slow process and can take up days if all should be transferred. Therefore the test must be constructed in a way there a shorter reaction time can be extrapolated into the right reading. Let us say that after 8 minutes 2 % of the real nitrate concentration is converted - the read nitrite concentration - you need to first multiply the figure you read with 50 and after that convert NO2 concentration into NO3 concentration - it means multiply with 1.35. This calculation is done by the meter or the colour chart. If your NO2 concentration is zero when you start the process - the result will be fine - but if you have 0.01 in nitrite from the beginning - also this will be multiplied with 50 and therefore give a false reading - in this example with 0.5 *1.35 = 0.675 ppm nitrate to much calculated. In my example - the asked factor is 67,5. What we need is that factor that is needed in order to calculate existing nitrite into read nitrate. Without that factor - the test is useless for most people. Of cause - Hanna have this factor or can measure it - if they want.

In Tropic Marine NO2/NO3 Pro test - this factor is 100.

Sincerely Lasse
 

chema

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I guess there is no news from Hanna.
I was about to buy the nitrate checker, but may be I should first verify whether I have some nitrite or not. Any experience with the Hanna nitrite checker?
 

robbyg

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I guess there is no news from Hanna.
I was about to buy the nitrate checker, but may be I should first verify whether I have some nitrite or not. Any experience with the Hanna nitrite checker?
It worked fine for me when I use to use it. The Nitrites were almost always zero or close to zero so I stopped testing and have not bought any reagents in a long time. I suspect that you will be fine with the Nitrate tester so long as you don't shoot for 1ppm or lower.
 

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