Hannah ULR phosphate checker accuracy

[hoytoyed]

Just got an icp test results back and either my phosphate checker is off or I can’t manage to administer the test accurately. My last icp test showed phosphate lower than I had recently tested so with this one I tested everything the same time I drew the water for the icp test.
I tested phosphate @ .13 and the icp came back .08. Can it be that far out or is it me? The test seems pretty straightforward- fill cuvette, zero then add reagent and shake for 2 minutes- push the button until it starts the 3 minute countdown.

 

[hoytoyed]

Disregard, I thought accuracy was +\- 5% but it’s .05 ppm. It’s within stated accuracy. Barely.

 

[taricha]

Disregard, I thought accuracy was +\- 5% but it’s .05 ppm. It’s within stated accuracy. Barely.

... and ICP vendors have no stated accuracy at all.
(Those two measurements are certainly within the combined uncertainties of the two methods)

 

[EricR]

Seems close enough.
FWIW, my Hanna Phosphate ULR always shows 0.02 less then my LFS Milwaukee

 

[92Miata]

... and ICP vendors have no stated accuracy at all.
(Those two measurements are certainly within the combined uncertainties of the two methods)

It's worse than that.


ICP can only measure elements. IE - it can only measure Phosphorus - not Phosphate. Any phosphate measurement coming from an ICP was either done via a standard test, or they took the phosphorus reading, made a bunch of assumptions and calculated a number based on those assumptions.

 

[Icedog]

I too was concerned about the validity of my phosphate measurements with the Hanna ULR Phosphate checker. I generally send out a sample of my tank water for ICP analysis on a monthly basis, either to ATI or Triton. And I also run testing myself with the Hanna checker on that same sample, just for comparison. And here are my results for the past six months:

The Hanna checker is always higher than the ICP, often by more than +/- 0.05 ppm. I'm guessing that the two testing methods aren't comparable, but I'm wondering which method to believe???

I have a softie tank, and I try to keep my phosphates below 0.1 ppm. So according to the ICP testing, I'm doing okay. But with the Hanna testing, I'm not.

 

[EricR]

I don't know anything about ICP tests but post #5 is interesting.
FWIW, my Hanna Phosphate ULR test is usually 0.01-0.02 ppm LOWER than my LFS Milwaukee test (on same water sample), at least the 3-4 times I've compared.

 

[taricha]

The Hanna checker is always higher than the ICP, often by more than +/- 0.05 ppm. I'm guessing that the two testing methods aren't comparable, but I'm wondering which method to believe???

Any chance that the hanna number is ppm Phosphate (PO4) and the ICP is Phosphorus (P). Or did you convert one for comparison?

 

[92Miata]

I too was concerned about the validity of my phosphate measurements with the Hanna ULR Phosphate checker. I generally send out a sample of my tank water for ICP analysis on a monthly basis, either to ATI or Triton. And I also run testing myself with the Hanna checker on that same sample, just for comparison. And here are my results for the past six months:

The Hanna checker is always higher than the ICP, often by more than +/- 0.05 ppm. I'm guessing that the two testing methods aren't comparable, but I'm wondering which method to believe???

I have a softie tank, and I try to keep my phosphates below 0.1 ppm. So according to the ICP testing, I'm doing okay. But with the Hanna testing, I'm not.

Said this above, and will say it again for the cheap seats.

ICPs (Inductively Coupled Plasma) can only test ELEMENTS. They work by taking your sample, heating it with plasma, and watching and measuring the emissions as it decays (with a mass spectrometer). An ICP test can't tell the difference between the phosphorus in a Phosphate molecule, an ATP molecule, attached to something's DNA, or as part of a piece of sand in your sample. Everything burns, everything looks the same.

Phosphate results returned on "Aquarium ICPs" are either done via a standard phosphate Ascorbic Acid Reduction test (like your test kits) - or they take the phosphorus reading, and adjust it by some unknown proprietary method. They are, at best, equally as accurate as your home test, and may be in fact significantly less accurate.


ICP tests should only be viewed as a source of truth for things like heavy metals.

 

[Reef.]

Disregard, I thought accuracy was +\- 5% but it’s .05 ppm. It’s within stated accuracy. Barely.

I don’t think ICP results on po4 are that accurate, as I understand it, they destroy all the phosphorus in the sample carrying out the other tests, then estimate the amount of PO4 that could have been present.

I would go with Hanna for po4.

 

[Icedog]

Any chance that the hanna number is ppm Phosphate (PO4) and the ICP is Phosphorus (P). Or did you convert one for comparison?

The Hanna checker results are PO4 in ppm and the ICP results are PO4 in mg/l. There isn't a need for a conversion factor to compare the two.

I redid the chart to show the units and included the results for phosporus - see below. I also added the normal values for each - ATI's is an "ideal value" and Triton's is a "setpoint".

 

[taricha]

The Hanna checker results are PO4 in ppm and the ICP results are PO4 in mg/l. There isn't a need for a conversion factor to compare the two.

I redid the chart to show the units and included the results for phosporus - see below. I also added the normal values for each - ATI's is an "ideal value" and Triton's is a "setpoint".

Ok. Thanks. I asked about the P vs PO4 because several of the values looked suspiciously like the 3:1 ratio of PO4 vs P .

You'll find @Rick Mathew work here interesting.
https://www.reef2reef.com/threads/s...nt-and-icp-measurement-results-part-2.737414/
He found that PO4 was routinely lower for him in ICP testing vs the hanna, and that the amount lower it was could be matched by storing the the samples in the shipping tubes and re-testing with hanna later (that is, loss over time in the tube).

Furthermore he found that chlorination of the samples (and in a follow-up article, acidification worked too) were sufficient to cause the hanna PO4 test and the triton ICP to agree very closely.
That is - by treating the samples to prevent biological activity over the time frame of shipping for ICP testing, suddenly the ICP and the hanna checkers agreed very tightly.

This doesn't affect everyone equally, but some people's water supports biological activity in shipping tubes that results in lower PO4 by the time it gets to ICP testing.

 

[Icedog]

Ok. Thanks. I asked about the P vs PO4 because several of the values looked suspiciously like the 3:1 ratio of PO4 vs P .

You'll find @Rick Mathew work here interesting.
https://www.reef2reef.com/threads/s...nt-and-icp-measurement-results-part-2.737414/
He found that PO4 was routinely lower for him in ICP testing vs the hanna, and that the amount lower it was could be matched by storing the the samples in the shipping tubes and re-testing with hanna later (that is, loss over time in the tube).

Furthermore he found that chlorination of the samples (and in a follow-up article, acidification worked too) were sufficient to cause the hanna PO4 test and the triton ICP to agree very closely.
That is - by treating the samples to prevent biological activity over the time frame of shipping for ICP testing, suddenly the ICP and the hanna checkers agreed very tightly.

This doesn't affect everyone equally, but some people's water supports biological activity in shipping tubes that results in lower PO4 by the time it gets to ICP testing.

Wow! I've often wondered if the storage time prior to ICP testing would affect the results of any of the parameters. It's usually a one-week turnaround time for Triton, and more like two weeks for ATI.

I appreciate the synopsis of the thread you posted and will certainly review the thread itself. This fascinates me! And it tells me to rely more so on the results of Hanna checker than the ICP tests, at least in the case of phosphates.

Thanks so much!

 

[KStatefan]

The Hanna checker results are PO4 in ppm and the ICP results are PO4 in mg/l. There isn't a need for a conversion factor to compare the two.

I redid the chart to show the units and included the results for phosporus - see below. I also added the normal values for each - ATI's is an "ideal value" and Triton's is a "setpoint".

The 7-22 data point looks off, highest phosphorus reading at 44.96 ppb and lowest phosphate reading at 0.014 ppm

 

[Icedog]

The 7-22 data point looks off, highest phosphorus reading at 44.96 ppb and lowest phosphate reading at 0.014 ppm

You're right - thanks for catching that error! It should've been 0.14 mg/l. See corrected chart below:

 

[Randy Holmes-Farley]

I too was concerned about the validity of my phosphate measurements with the Hanna ULR Phosphate checker. I generally send out a sample of my tank water for ICP analysis on a monthly basis, either to ATI or Triton. And I also run testing myself with the Hanna checker on that same sample, just for comparison. And here are my results for the past six months:

The Hanna checker is always higher than the ICP, often by more than +/- 0.05 ppm. I'm guessing that the two testing methods aren't comparable, but I'm wondering which method to believe???

I have a softie tank, and I try to keep my phosphates below 0.1 ppm. So according to the ICP testing, I'm doing okay. But with the Hanna testing, I'm not.

Since phosphate can change in a sample stored for days or longer (say, bacteria or algae on the sides of the container took up some P), I think it is not necessarily valid to claim they are giving different results, but the methods do test different things.

That said, ICP should always read as high or higher than a kit test (sicne it detects all dissolved forms fo P while the Hanna kit won't), unless the kit test is somehow dissolving particulate material that got into the test where the ICP somehow filtered it out first.

 

[Sdot]

A little backstory on my tank, its nutrient deficient. I've always had to dose both phos and nitrate. With that said, my experience with hanna phosphorus testers have not been positive. I notice my alk would go up and my colors bleaching. When testing for phos using the hanna it would often report much much higher levels. My last experience with this was confirmed by an icp test. My hanna reported .5 phos while icp test was near zero. I also understand it takes several weeks for the ICP test to send results, and the sample water chemistry can change in that time. My next step was to compare testing results from two different testers.... A milwaukee 412 and hanna phosphate tester.

Hanna reported .08 phosphate while the milwaukee test resulted in 0. I started dosing more phos to settle the experiment. After a week, i noticed colors starting to return and my alk consumption going up. When testing again with the milwaukee, it resulted in .03 of phosphate, the hanna stated 150ppb which is .4 ppm! FYI i usually purchase calibration cuvettes for hanna and calibrate every 6 months. I did test and according to the calibration, the tester is still good. Needless to say i have retired my hanna. Lesson....listen to your tank....use test to confirm and use ICP test to confirm test.

 

[92Miata]

A little backstory on my tank, its nutrient deficient. I've always had to dose both phos and nitrate. With that said, my experience with hanna phosphorus testers have not been positive. I notice my alk would go up and my colors bleaching. When testing for phos using the hanna it would often report much much higher levels. My last experience with this was confirmed by an icp test. My hanna reported .5 phos while icp test was near zero. I also understand it takes several weeks for the ICP test to send results, and the sample water chemistry can change in that time. My next step was to compare testing results from two different testers.... A milwaukee 412 and hanna phosphate tester.

Hanna reported .08 phosphate while the milwaukee test resulted in 0. I started dosing more phos to settle the experiment. After a week, i noticed colors starting to return and my alk consumption going up. When testing again with the milwaukee, it resulted in .03 of phosphate, the hanna stated 1.5ppm! FYI i usually purchase calibration cuvettes for hanna and calibrate every 6 months. I did test and according to the calibration, the tester is still good. Needless to say i have retired my hanna. Lesson....listen to your tank....use test to confirm and use ICP test to confirm test.

Yeah, it's probably working fine. You bought the the wrong meter. None of the meters designed for this range go anywhere near 1.5 ppm (HI774 maxes out at .9, HI736 at about .6). You're way outside what the HI713 and the Milwaukee 412 are designed to measure.

 

[Sdot]

Yeah, it's probably working fine. You bought the the wrong meter. None of the meters designed for this range go anywhere near 1.5 ppm (HI774 maxes out at .9, HI736 at about .6). You're way outside what the HI713 and the Milwaukee 412 are designed to measure.

Sorry correction... not 1.5ppm but 150ppb which would be .4. Needless to say I don't trust the Hannah phosphate checker. I would never dose more phos if my levels where .4.... I will say so far in my experience the milwaukee to be more consistent and closer to accurate.

 

[92Miata]

Sorry correction... not 1.5ppm but 150ppb which would be .4. Needless to say I don't trust the Hannah phosphate checker. I would never dose more phos if my levels where .4.... I will say so far in my experience the milwaukee to be more consistent and closer to accurate.

The stated accuracy of the milwaukee meter is +/- .07 @ 1ppm - and it's designed to be used around that calibration point. The HI-736 is much, much more accurate, especially in that .03 range.

Either you've got a defective HI-736, bad reagent, the wrong reagent, or you're doing something wrong in your testing process.