Test kit inconsistency...?

[SoSublime]

Hello.

I recently purchased a Hanna HR nitrate meter.

The problem is, my numbers vary so much between it, and my other test kit, im not sure which to believe.

I purchased the "certified standard kit" from Hanna, and it reads in range to the standards acceptable limits for the meter.

However. My Nyos kit, unexpired, and upon repeat tests, shows nearly a 20ppm lower test. Hanna was reading 35ppm, Nyos matching the 12ppm color.

I ran the Nyos 3 times in this tank, and twice against my other two tanks, against the Hanna. For the sake of it I also used a Salifert kit I have. (Salifert expires in 2023, Nyos in 2023, and Hanna in 2026".

Followed all the direction for all test kits to a T, using new syringes for every test.

My other two tanks, the results all line up as expected of good tests, 0-5ppm nitrate.

On one tank however:
Nyos - approx for 3 tests 12ppm, after last WC around 5ppm
Salifert - 1st test 50+ppm nearing 100ppm in color, 2nd test (with no WC) 25ppm, final test after last WC 10-25ppm (didn't bother running it twice because it really didn't change with another WC and still appeared to have close to the same color as before WC)
Hanna - first test 35ppm, 2nd test 39.9ppm, and final test after last WC is 21ppm

So in two other tanks, the results match, in this tank they don't.

FWIW I ran phosphate tests against the water changes also. Was at 91ppb, then to 35ppb, then now I am 13ppb. Matching the total 85% dilution from WCs the water should have had.

Now some background, this tank is about 10G actual water volume.
I've done 3 4.5G water changes because my original Nyos test before these inconsistencies said my nitrate was high, around 40ppm which didnt suprise me as I have been sick these last 2 months. 3 4.5g water changes should be greater than 85% of dilution.
Meaning if I was to believe the Hanna meter, my nitrates would have to have been nearly 200ppm. With the original Salifert test, they would have had to been well over 200ppm.
And the Nyos would have been around 40ppm.

Now there is zero major algae in this tank. The only real algae present is slow growing film on glass, and a small amount of bubble algae that doesn't really spread. Fish have never acted abnormal. Inverts never have been affected.

Where am I supposed to go from here? The actual number is irrelevant to me, as I don't "chase" them, I would just like to know what my real number is as I have had dinos in the past, and want to refrain from bottoming out nutriets and don't know how to determine that with such wide inconsistencies.

If the Hanna is correct, I'm still quite high on nitrates. I think the salifert is a bad kit. And if the Nyos is correct, I'm right on the money.

 

[Lasse]

So in two other tanks, the results match, in this tank they don't.

Probably because of rather high nitrite levels in your "trouble" tank. Because the construction of these tests - nitrite is a major interfering ion in the nitrate measurement. The different test will be interfered in different conversion factors. For salifert - I know that the factor is around 50 - it means that if you have 0,1 ppm nitrite - it will add 5 ppm to your nitrate readings. If you have a true content of 10 ppm NO3 and 0.1 ppm NO2 - your reading with salifert will give you 15 ppm NO3. I have tested the factor for Hanna HR and when I use a 1 ppm NO2 standard - 0 NO3 - I read around 8 ppm NO3. I normally calculate with a factor of 10 with Hanna. Nyos - I do not know the factor.

The problem is that it is difficult to measure low nitrite values - IMO - only Hanna Marine ULR NO2-N meter is useful if your colour vision not is 100%. If it is good - Fauna Marine NO2/NO3 kit and Tropic marines Pro NO2/NO3 kits are good

Sincerely Lasse

 

[SoSublime]

Probably because of rather high nitrite levels in your "trouble" tank. Because the construction of these tests - nitrite is a major interfering ion in the nitrate measurement. The different test will be interfered in different conversion factors. For salifert - I know that the factor is around 50 - it means that if you have 0,1 ppm nitrite - it will add 5 ppm to your nitrate readings. If you have a true content of 10 ppm NO3 and 0.1 ppm NO2 - your reading with salifert will give you 15 ppm NO3. I have tested the factor for Hanna HR and when I use a 1 ppm NO2 standard - 0 NO3 - I read around 8 ppm NO3. I normally calculate with a factor of 10 with Hanna. Nyos - I do not know the factor.

The problem is that it is difficult to measure low nitrite values - IMO - only Hanna Marine ULR NO2-N meter is useful if your colour vision not is 100%. If it is good - Fauna Marine NO2/NO3 kit and Tropic marines Pro NO2/NO3 kits are good

Sincerely Lasse

Nitrite is absolute zero, without a doubt. Not even the slightest hint of color at all, completely bleach white.

Tank is also nearly 2 years old. Is not fed super heavily nor stocked heavy. Only 2 clowns who have been in since 3 months after tank was started and CUC, fed twice a day, all food is consumed.

I would be surprised if any nitrite could be present given the test. And while it's a good theory and anything is possible that as you said it's due to a exponentially small amount of nitrite, I would also expect the Nyos kit to be affected, raising all the readings, rather than all readings being over +/-20ppm away from eachother.

And given your calculated factor, to get from Nyos' 12ppm to Hannas 40ppm, that would require around 3.5ppm of nitrite correct? And saliferts would require greater than 1ppm of nitrite present as its initial reading was well above 50, nearing 100 on the chart. I am fairly confident I would see this on the nitrite test and did not.

Tested full panel
0 - ammo
0 - nitrite
Hanna - 22-23ppm & Nyos 5ppm - nitrate.
Phos - 13ppb Hanna
PH 8.1 - Calibrated digital meter.
Alk - 9.2dKH Hanna
Cal - 410ppm - Red Sea
Mag - 1250ppm - Red sea

Tested RO/DI
0TDS on both outflow meter and handheld. All testable parameters 0.

 

[Lasse]

If it not nitrite - you need to figure out which ion in the third aquarium that is responsible for the interference in your measurement. as I understand - your three tests shows nearly the same figures in two of your aquariums but differ total in the third. The problem - IMO - is not in your test or your two aquariums - the problem must be with some disturbing ion in the third - and that the interference is different between the tests

sincerely Lasse

 

[SoSublime]

If it not nitrite - you need to figure out which ion in the third aquarium that is responsible for the interference in your measurement. as I understand - your three tests shows nearly the same figures in two of your aquariums but differ total in the third. The problem - IMO - is not in your test or your two aquariums - the problem must be with some disturbing ion in the third - and that the interference is different between the tests

sincerely Lasse

I guess the only other thing to do would be try an ICP test and see if anything abnormal appears.

I'm doing 1 more 4.5G WC because it will put me in a comfortable range for either test, and will order a test to see if I can rule it out. At that point dilution should be near only 8% of original water and I'll see if the test line up at these lower nitrate levels.

Not sure what it could be as they all get the same food, water, salt, etc. But I guess it's a waiting game.

 

[Lasse]

I guess the only other thing to do would be try an ICP test and see if anything abnormal appears.

I'm doing 1 more 4.5G WC because it will put me in a comfortable range for either test, and will order a test to see if I can rule it out. At that point dilution should be near only 8% of original water and I'll see if the test line up at these lower nitrate levels.

Not sure what it could be as they all get the same food, water, salt, etc. But I guess it's a waiting game.

Nitrate is rather difficult to analyze in saltwater because of disturbing ions. Here in Europe - there is one aquaristic lab that analyse nitrate and nitrite with scientific equipment (a special form of ion chromatography) I normally send in a test 1-2 times a year to them in order to get a base for my nitrate and nitrite and a possibility to fine tuning my normal measurements. It is Oceamo in Austria. In the US I know that Aquabiomics cooperate with them. I normally use Triton tests (I have a database of 22 result through the last 5.5 years) but for a check up (they do not differ very much in the normal ICP tests. ) and get figures of compounds that not is included (or below detection limit) with i normal ICP tests - its a good tool.

Sincerely Lasse

 

[SoSublime]

Nitrate is rather difficult to analyze in saltwater because of disturbing ions. Here in Europe - there is one aquaristic lab that analyse nitrate and nitrite with scientific equipment (a special form of ion chromatography) I normally send in a test 1-2 times a year to them in order to get a base for my nitrate and nitrite and a possibility to fine tuning my normal measurements. It is Oceamo in Austria. In the US I know that Aquabiomics cooperate with them. I normally use Triton tests (I have a database of 22 result through the last 5.5 years) but for a check up (they do not differ very much in the normal ICP tests. ) and get figures of compounds that not is included (or below detection limit) with i normal ICP tests - its a good tool.

Sincerely Lasse

Awesome, thanks for the info.

For now after the last WC were at 3-10ppm on nitrate depending on the test, so I'm good there for the time being. Gives me some wiggle room to figure out the root.