Phosphate testing

[BuffaloLake]

there is no other way to be 100% than you make a reference fluid and based on that calibrate the Trident and/or check the Hanna.

The Trident comes with a calibration solution in each reagent set.

Yes, but this is the Trident NP nitrate and phosphate only. The calibration fluid that they send out only calibrates the head pressure on the sample line. It doesn’t contain either N or P to calibrate the results. To perform a calibration, you must prepare your own sample with known values. I was using my Hanna checkers to do this, but then my ICP results made me question my Hanna.

 

[areefer01]

Yes, but this is the Trident NP nitrate and phosphate only. The calibration fluid that they send out only calibrates the head pressure on the sample line. It doesn’t contain either N or P to calibrate the results. To perform a calibration, you must prepare your own sample with known values. I was using my Hanna checkers to do this, but then my ICP results made me question my Hanna.

Do you have a source for this information? The calibration solution for the NP is known and preset. You do not enter a value on the nor is there any value on the bottles. It does not do any pressure testing on the sample lines or manifold.

The manual calibration option was only added after the release as hobbyist wanted to closer align with their manual test kits. If you go with your manual test results the recommended way is to collect a pint of water, from the sample line area, run 4 to 5 tests, discard any anomalies, enter those values, then use the remaining water to calibrate.

 

[BuffaloLake]

Yes, but this is the Trident NP nitrate and phosphate only. The calibration fluid that they send out only calibrates the head pressure on the sample line. It doesn’t contain either N or P to calibrate the results. To perform a calibration, you must prepare your own sample with known values. I was using my Hanna checkers to do this, but then my ICP results made me question my Hanna.

Do you have a source for this information? The calibration solution for the NP is known and preset. You do not enter a value on the nor is there any value on the bottles. It does not do any pressure testing on the sample lines or manifold.

The manual calibration option was only added after the release as hobbyist wanted to closer align with their manual test kits. If you go with your manual test results the recommended way is to collect a pint of water, from the sample line area, run 4 to 5 tests, discard any anomalies, enter those values, then use the remaining water to calibrate.

“Additionally, the Trident is factory calibrated upon your receipt of the unit. The calibration process simply allows for the Trident to be calibrated to your specific installation- such as sample line head height. Do not expect drastic changes in your measurements compared to before and after the calibration.”


This is directly from Neptunes website on the NP. They spell out that it calibrated head height, and that you shouldn’t expect the readings to change.

 

[areefer01]

“Additionally, the Trident is factory calibrated upon your receipt of the unit. The calibration process simply allows for the Trident to be calibrated to your specific installation- such as sample line head height. Do not expect drastic changes in your measurements compared to before and after the calibration.”


This is directly from Neptunes website on the NP. They spell out that it calibrated head height, and that you shouldn’t expect the readings to change.

I am aware of that. That is for the installation which will vary among us. The calibration task provides an option for using the included solution (known values) or hobbyist manual test results. That was my point. The values are used and tests are conducted.

The sample line is important which is why it can't be modified. But the calibration task is still that, a calibration routine to a known, or entered, value.

 

[BuffaloLake]

“Additionally, the Trident is factory calibrated upon your receipt of the unit. The calibration process simply allows for the Trident to be calibrated to your specific installation- such as sample line head height. Do not expect drastic changes in your measurements compared to before and after the calibration.”


This is directly from Neptunes website on the NP. They spell out that it calibrated head height, and that you shouldn’t expect the readings to change.

I am aware of that. That is for the installation which will vary among us. The calibration task provides an option for using the included solution (known values) or hobbyist manual test results. That was my point. The values are used and tests are conducted.

The sample line is important which is why it can't be modified. But the calibration task is still that, a calibration routine to a known, or entered, value.

I don’t have that option, and I have never found anything on the Neptune website about this. If I go to the task menu, the initial calibration for head pressure is the only option. If you go directly to the Trident NP tab, you can perform a manual calibration with values that you enter in, But there is no option for calibration with the Trident solution.

 

[areefer01]

I don’t have that option, and I have never found anything on the Neptune website about this. If I go to the task menu, the initial calibration for head pressure is the only option. If you go directly to the Trident NP tab, you can perform a manual calibration with values that you enter in, But there is no option for calibration with the Trident solution.

You may be misunderstanding, or I am not explaining it well. In either case the Trident NP reagent set includes a calibration solution. This solution is known and the values are pre-set. We can't change those. The original instructions below. I am not talking about using the Trident ACM (alk, ca, and mg) solution as that is different.

Neptune later updated the NP's firmware to allow the hobbyist to calibrate the NP using manual test results. This has been something that existing Trident ACM users have been doing for a good while now and requested that the NP do the same. So Neptune made the change.

If you got to tasks you will see in the list Trident NP calibration. That will give you the option to either use the included calibration solution that came with the NP's reagents, or let you enter your own values. If you select the included solution you won't be able to enter values - it is known. If you select manual, then you enter your values. You place the sample line in the calibration, or your test water or reference then the NP does its thing.

Note: if you do not see either of these options then you are on an older firmware and would need to update.

https://help.neptunesystems.com/getstarted/tridentnp/calibration/

 

[KrisReef]

Not as consistent as they should be. This morning I filled two cuvettes with tank water. Added Hanna reagent to one for C2, kept the other as C1. I then ran those same samples repeatedly. Results were 0.55, 0.64, 0.56, 0.47, 0.61.

My Hanna ULR reports in PPB, and I have to convert that into ppm. Are these converted values, or ppb, or?

 

[BuffaloLake]

I don’t have that option, and I have never found anything on the Neptune website about this. If I go to the task menu, the initial calibration for head pressure is the only option. If you go directly to the Trident NP tab, you can perform a manual calibration with values that you enter in, But there is no option for calibration with the Trident solution.

You may be misunderstanding, or I am not explaining it well. In either case the Trident NP reagent set includes a calibration solution. This solution is known and the values are pre-set. We can't change those. The original instructions below. I am not talking about using the Trident ACM (alk, ca, and mg) solution as that is different.

Neptune later updated the NP's firmware to allow the hobbyist to calibrate the NP using manual test results. This has been something that existing Trident ACM users have been doing for a good while now and requested that the NP do the same. So Neptune made the change.

If you got to tasks you will see in the list Trident NP calibration. That will give you the option to either use the included calibration solution that came with the NP's reagents, or let you enter your own values. If you select the included solution you won't be able to enter values - it is known. If you select manual, then you enter your values. You place the sample line in the calibration, or your test water or reference then the NP does its thing.

Note: if you do not see either of these options then you are on an older firmware and would need to update.

https://help.neptunesystems.com/getstarted/tridentnp/calibration/

Ok, you are right. I will calibrate using a fresh calibration solution.

 

[BuffaloLake]

Not as consistent as they should be. This morning I filled two cuvettes with tank water. Added Hanna reagent to one for C2, kept the other as C1. I then ran those same samples repeatedly. Results were 0.55, 0.64, 0.56, 0.47, 0.61.

They make two versions of the ULR. The phosphorus version (ppb) requires conversion to get phosphate. The phosphate version (ppm) does not. I have the phosphate version, so mine is in ppm

 

[areefer01]

Ok, you are right. I will calibrate using a fresh calibration solution.

Well to be honest I am not saying either of us are wrong but rather just trying to explain how the NP calibrates and what Neptune changed. There are a few posts here and there with hobbyist not liking the NP's calibration solution.

With both of my Tridents (ACM, NP) I calibrate between 48 and 72 hours after new reagent swap. The wait time is to make sure it is consistent with the results. It doesn't have to be accurate but it has to be close to the previous test so I know lines are not kinked, or filter blocked, etc. Once I see the pattern then I run the calibration.

With the Trident ACM I use their included solution. With the Trident NP I use manual test results. I've done both with the NP but for now I like the manual calibration numbers since my tank runs higher nutrients. It also allows me to spot check if I see a result higher, or lower, than normal.

Hope your day is well.

 

[EnterName]

My Hanna ULR reports in PPB, and I have to convert that into ppm. Are these converted values, or ppb, or?

To get from ppb P to ppm PO₄ you need to multiply with 0.00307 or divide by 326.2.

Phosphorus (P) has a molar mass of 30.974g/mol,
Phosphate (PO₄) has a molar mass of 94.97g/mol

94.97g/mol PO₄ / 30.974g/mol P ≈ 3.066
​

So the direct conversion between P and PO₄ works with the factor 3.066 (or divisor 0.3262).
But don't forget the conversion from ppb to ppm, so you need to scale with 1000:

3.066 / 1000 ≈ 0.003066 (multiply by this)
0.3262 ⋅ 1000 ≈ 326.2 (or divide by this)
​

Example:
If your ppb ULR Phosphorus checker reads 12ppb P you can get ppm PO₄ by:

12ppb P ⋅ 0.00307 ≈ 0.037ppm PO₄
12ppb P / 326.2 ≈ 0.037ppm PO₄​

 

[KrisReef]

To get from ppb P to ppm PO₄ you need to multiply with 0.00307 or divide by 326.2.

Phosphorus (P) has a molar mass of 30.974g/mol,
Phosphate (PO₄) has a molar mass of 94.97g/mol

94.97g/mol PO₄ / 30.974g/mol P ≈ 3.066
​

So the direct conversion between P and PO₄ works with the factor 3.066 (or divisor 0.3262).
But don't forget the conversion from ppb to ppm, so you need to scale with 1000:

3.066 / 1000 ≈ 0.003066 (multiply by this)
0.3262 ⋅ 1000 ≈ 326.2 (or divide by this)
​

Example:
If your ppb ULR Phosphorus checker reads 12ppb P you can get ppm PO₄ by:

12ppb P ⋅ 0.00307 ≈ 0.037ppm PO₄
12ppb P / 326.2 ≈ 0.037ppm PO₄​

Yes .
I was just wondering what version of the Hanna ULR our op was reporting results from, because by coincidence the numbers reported didn’t have ppm or ppb and the conversion (if it was not present) might have explained some of the difference between the other methods reported.

It was not a factor here as the original data (was clarified) as ppm, read straight from the meter version that reports ppm.

I was barking in the wind,…

 

[EnterName]

Yes .
I was just wondering what version of the Hanna ULR our op was reporting results from, because by coincidence the numbers reported didn’t have ppm or ppb and the conversion (if it was not present) might have explained some of the difference between the other methods reported.

It was not a factor here as the original data (was clarified) as ppm, read straight from the meter version that reports ppm.

I was barking in the wind,…

Ah, okay, sorry. In my defense, English is my second language and reading comprehension is apparently my third.

I will just blame the language barrier and quietly leave the thread

 

[KrisReef]

Ah, okay, sorry. In my defense, English is my second language and reading comprehension is apparently my third.

I will just blame the language barrier and quietly leave the thread

I’m familiar with your language “challenge “and I hope my response translates well and with kindness.?
Today, I am a bit tired from yard work and I don’t want to translate my weariness into anything that could be perceived as offensive or hostile.

Sorry if I offended, mein herr! My German isn’t sehr gut and my spelling and grammar are my low marks historically, in any language other than sign language

Party like a movie star!

 

[Randy Holmes-Farley Verified Community Expert]

In my opinion, the potential loss of phosphate in shipped samples is mainly caused by biological activity and the formation of a biofilm on the inside of the sample vial. Phosphate can be taken up and bound by this biofilm. Since only the aqueous sample is used for ICP and photometric measurement, while the biofilm remains attached to the tube walls, this phosphorus is effectively lost from the analysis.

We try to minimize biological activity in the sample by filtering it through a 0.22 µm filter immediately during sampling. However, the sample will never be completely sterile, and some biological activity can still occur during transport. For this reason, we add a stabilizer to the tube dedicated to phosphate measurement in our ICP-MS test kit.

Interestingly, even in systems without any measurable orthophosphate, we usually detect some phosphorus by ICP. ICP measures elemental phosphorus irrespective of its chemical form, so phosphorus species other than orthophosphate contribute to this result as well.

At the moment, we are not able to fully speciate these phosphorus compounds, so their bioavailability remains a big question mark. Having detectable total P while orthophosphate is undetectable might therefore be perfectly fine, but it could also indicate actual phosphate limitation. I don't think we can say for sure, especially since the profile of these "non-orthophosphate phosphorus species" may be very different between individual aquariums.

Usually, this non-orthophosphate phosphorus fraction is relatively small. At higher orthophosphate concentrations, ICP-P and orthophosphate therefore tend to agree quite well, because this small background contribution becomes insignificant compared with the overall concentration and measurement uncertainty.

Interestingly, from time to time we encounter aquariums with very high phosphorus concentrations while orthophosphate remains surprisingly low or even undetectable. So far, I have not been able to identify which phosphorus species are responsible for these cases.

All the best,

Christoph

Thank you, Christoph. :)