Hanna PO4 vs. ICP

Bubblebass

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Long story short - tank has some gha. Hanna phosphorous checker was reading 8 (converted to 0.024 PO4). Sent in an ICP and received it back with a phosphorus reading over 100 and PO4 over 0.3. Borrowed a friends phosphorous checker and both are reading exactly the same thing. Still 8. Originally it read high so I started some gfo.

I am aware that some PO4 can be bound in the GHA. But would this mean a different reading on the ICP and Hanna checkers? Wouldn't it be the same in the water either way?

The GHA is not better and looks to be getting worse. I also have some cyano on the sand now.

NO3 15
Alk 8.3
Mag 1450
Cal 450
Tank is an IM40 running a small skimmer (9004) and floss.

I want to get rid of the GHA, but if I don't know my PO4 levels, I'm not sure how to proceed. I have plenty of CUC.
 

Sean Clark

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Did you happen to test with your hanna at the same time that you filled your ICP sample vials?
 
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Bubblebass

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Did you happen to test with your hanna at the same time that you filled your ICP sample vials?
yes. That’s the dilemma. Same numbers then and now. So odd. I even contacted Hanna support who was great, but they said all they can do it test against their standards there. I figure if two of their checkers are saying the same thing, how can they be off by THAT much?
 

Sean Clark

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I attached two ICP tests that I did in September on the same day. All I was trying to do was verify the consistency of the results.

I just looked at the Phosphorus for both of them and it is quite interesting. Test 1 shows 30.06 ppb Phosphorus. Test 2 shows 3.43 ppb Phosphorus. I don't know where you had your ICP done, but tis looks very much like your 10 times too high results.
 

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Bubblebass

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I attached two ICP tests that I did in September on the same day. All I was trying to do was verify the consistency of the results.

I just looked at the Phosphorus for both of them and it is quite interesting. Test 1 shows 30.06 ppb Phosphorus. Test 2 shows 3.43 ppb Phosphorus. I don't know where you had your ICP done, but tis looks very much like your 10 times too high results.
Wow. That’s crazy. Thank you for this. What was your home checker showing at the time? Also, I’m not sure if that test showed your nitrates? What we’re they at the time? I used ATI ICP. Which test brand was yours?
 

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Long story short - tank has some gha. Hanna phosphorous checker was reading 8 (converted to 0.024 PO4). Sent in an ICP and received it back with a phosphorus reading over 100 and PO4 over 0.3. Borrowed a friends phosphorous checker and both are reading exactly the same thing. Still 8. Originally it read high so I started some gfo.

I am aware that some PO4 can be bound in the GHA. But would this mean a different reading on the ICP and Hanna checkers? Wouldn't it be the same in the water either way?

The GHA is not better and looks to be getting worse. I also have some cyano on the sand now.

NO3 15
Alk 8.3
Mag 1450
Cal 450
Tank is an IM40 running a small skimmer (9004) and floss.

I want to get rid of the GHA, but if I don't know my PO4 levels, I'm not sure how to proceed. I have plenty of CUC.

Can you post the actual ICP results?
 
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Bubblebass

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Can you post the actual ICP results?
ICP results

Here's a pic of the nutrient section in case I did the link wrong

Screen Shot 2022-01-24 at 5.15.04 PM.png
 

Randy Holmes-Farley

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Well, it certainly doesn't match the Hanna. Not sure why. They do not need to match as they measure different things, ICP measures organic and inorganic forms while the Hanna is just inorganic orthophosphate), but the difference is unlikely to be that large.
 
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Well, it certainly doesn't match the Hanna. Not sure why. They do not need to match as they measure different things, ICP measures organic and inorganic forms while the Hanna is just inorganic orthophosphate), but the difference is unlikely to be that large.
I was thinking of getting the Hanna standards for the phosphorous checker. That work give me an idea of how far off it is, right?
 

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I was thinking of getting the Hanna standards for the phosphorous checker. That work give me an idea of how far off it is, right?
Borrowed a friends phosphorous checker and both are reading exactly the same thing. Still 8.

You already verified your hanna against another one. No need to pay for hanna standards.

I would perform a standard Phosphate test with RedSea or Salifert, something like that. See what they say.
 
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If it wasn’t for the gha, I’d disregard the icp results as an error. The cyano also leads me to believe the phosphates may be low and the NO3 at the higher end. Maybe I’ll just get another icp going. Stumped at this point.
 

Sean Clark

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Wow. That’s crazy. Thank you for this. What was your home checker showing at the time? Also, I’m not sure if that test showed your nitrates? What we’re they at the time? I used ATI ICP. Which test brand was yours?
Sorry I missed this earlier.
I don't have a Phosphorus checker so I do not have my own measurement for that.
Phosphate was 0.02-0.03 with RedSea.
The ICP test that I used does not report Nitrate. My logs for September 7 show 2ppm Nitrate with RedSea and 0ppm with Hanna HR.
I used ICP-ANALYSIS.COM
 

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I was thinking of getting the Hanna standards for the phosphorous checker. That work give me an idea of how far off it is, right?

No.

Hanna standards aren't really able to evaluate the performance of the test. They are just colored water and they only check the electronics. A true phosphate in seawater standard would also check the reagents and the exact protocol employed by the user.
 
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Bubblebass

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No.

Hanna standards aren't really able to evaluate the performance of the test. They are just colored water and they only check the electronics. A true phosphate in seawater standard would also check the reagents and the exact protocol employed by the user.
Randy, what would you suggest I do from here? The protocol for 0.3 PO4 is the opposite for that of 0.02 with presence of gha. I have some reeflux on hand as well as gfo. The gha has been hanging on since the Hanna read about .1 and I started with gfo a few months ago. Also been debating trading in my silly, tiny skimmer for a small algae scrubber.
 

Dan_P

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Long story short - tank has some gha. Hanna phosphorous checker was reading 8 (converted to 0.024 PO4). Sent in an ICP and received it back with a phosphorus reading over 100 and PO4 over 0.3. Borrowed a friends phosphorous checker and both are reading exactly the same thing. Still 8. Originally it read high so I started some gfo.

I am aware that some PO4 can be bound in the GHA. But would this mean a different reading on the ICP and Hanna checkers? Wouldn't it be the same in the water either way?

The GHA is not better and looks to be getting worse. I also have some cyano on the sand now.

NO3 15
Alk 8.3
Mag 1450
Cal 450
Tank is an IM40 running a small skimmer (9004) and floss.

I want to get rid of the GHA, but if I don't know my PO4 levels, I'm not sure how to proceed. I have plenty of CUC.
Trust only the Hanna results for your phosphate measurement. The accuracy of ICP measurements can be low or high. You just never know which it will be. Changes in the sample during shipping combined with the variability of the ICP method itself make phosphorous measurement by ICP unreliable.
 
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Bubblebass

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Trust only the Hanna results for your phosphate measurement. The accuracy of ICP measurements can be low or high. You just never know which it will be. Changes in the sample during shipping combined with the variability of the ICP method itself make phosphorous measurement by ICP unreliable.
Sounds good to me. Just funny that the $45 ICP analysis would be less accurate than the hobby grade test equipment.
 

Randy Holmes-Farley

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Sounds good to me. Just funny that the $45 ICP analysis would be less accurate than the hobby grade test equipment.
Thought of differently, ICP is actually quite inexpensive by industry standards, and I think that can be a main issue with it.

I send out samples for work (not seawater) for analysis of a single chemical for which there is an existing analytical method. It costs $80 for a single chemical to be analyzed in a single sample, and there is a minimum fee of $4,000 if I do not have a bunch of identical samples to test.

For that cost, I expect a single high quality answer.

The ICP cost is only a dollar or two for each chemical analyzed! How much time could an expert operator spend on each sample?
 

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Sounds good to me. Just funny that the $45 ICP analysis would be less accurate than the hobby grade test equipment.
Hobby grade tests unfairly get a bad name. We rarely consider operator error as the principle reason for the poor results.

As for ICP result accuracy, that’s actually our fault too. We continue to not notice that the vendors do not give us any precision and accuracy information about their test results. They never promised accurate results :)
 

Fishingandreefing

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Sorry I missed this earlier.
I don't have a Phosphorus checker so I do not have my own measurement for that.
Phosphate was 0.02-0.03 with RedSea.
The ICP test that I used does not report Nitrate. My logs for September 7 show 2ppm Nitrate with RedSea and 0ppm with Hanna HR.
I used ICP-ANALYSIS.COM
Do you find the icp-analysis.com reliable and will use it again? I am just trying to get something affordable. Thx
 

Sean Clark

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Do you find the icp-analysis.com reliable and will use it again? I am just trying to get something affordable. Thx
Great question. Short answer: yes and yes.

I use icp-analysis.com because it is cheap and the turnaround is fast. I will use them again for the same reasons. When I posted my results above it was not meant to reflect poorly on icp-analysis.com or any ICP test. I was only trying to demonstrate how ICP tests are not perfect. There are so many factors that go into the accuracy of the test that I can not even pretend to understand.

Just because you get a result that looks off does not automatically mean that the result is something that you should act on right away. It also does not mean that ICP is terrible.

If you compare all of the elements from both test you will find that they are indeed very close on almost all of the results. The variances are typically well within the margin of error for our home test kits.

People have had ICP shootout style competitions where they send the same water out to all of the big ICP testing services and they come up with mixed results.
Pick one or try them all. I will probably get some flack for saying this but I don't think any of them are "bad" or "better" than another.
They all offer something that the customer values. Speed of results, more elements tested, "better" user interface, supplements and guided instructions, price point, etc.
 

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