These ICP numbers can't be right...can they?

Joe31415

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Just got back my first ICP test on a tank that's just starting to hit a year old and started with dry rock from BRS. Most of the numbers came back fine, but a few were so far off that I have to question them. I know the idea is generally that ICP is correct and your home test is wrong, I'm just not sure here.

I've been using a Hanna Phosphate ULR tester since the beginning. Through every batch of reagent I've used, it's always returned numbers that were right in line with the most recent tests. I don't have my notes in front of me, but off the top of my head, I believe it's been in the .03-.04 range. ICP gave me a result of 133 µg/l for Phosphorus and 0.40698 mg/l for Phosphate.

The Hanna Phosphate ULR tops out at .9, so I wasn't even close to pegging it and, like I said, I've never had any issues going from one batch of reagent to the next, so I don't think the reagent is an issue.

I know the ICP tests tend to read higher (free vs bound elements or something along those lines), but from what I've read, they tend to be about double, but if I'm reading and understanding everything correctly, one of us is wrong by an order of magnitude.


While I'm here, the other ones that Triton seemed concerned with are Tin at 17, Antimony at 27, which my reading suggests this tends to be due to something electronic that's in contact with the water or something corroding. I'll check my heaters but I don't think either of them are broken or rusting. I do have one metal hose clamp on part of the return pump line that developed a white dust on it, but it's probably 18 inches above the water.
Lithium is at 397
Barium is at 46
Silicon is at 540 (but I don't have any big algae outbreaks)
In fact, here's the entire report if anyone wants to see it.
It's probably also worth noting that everything appears to be doing fine. Corals are getting bigger, fish/shrimp/snails/crabs also appear to be growing. In other words, I did the ICP test more out of curiosity (and to have a baseline) than to solve a problem.
 

Randy Holmes-Farley

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The lithium and barium are of no concern to me.

Silicate is only ever any concern if you have problematic levels of diatoms.

tin may be from plastic tubing, but may not be high enough to be a problem.

Antimony seems sometimes associated with a UV from Green Killing Machine.

0.4 ppm phosphate from the ICP wouldn't max out the hanna, but I don't know which is correct. Could even be both are correct (though not likely) or neither. lol
 
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Joe31415

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The lithium and barium are of no concern to me.

Silicate is only ever any concern if you have problematic levels of diatoms.

tin may be from plastic tubing, but may not be high enough to be a problem.

Antimony seems sometimes associated with a UV from Green Killing Machine.
That's basically what I read about all these things, so I wasn't tooo concerned about any of them.

0.4 ppm phosphate from the ICP wouldn't max out the hanna,
Yes, sorry, that's what I was saying. My concern was that if the Hanna tester I had maxed out at, say, .05 my phosphates could have been way above what I thought they were at and I'd never have known it. But that's not the case here. If I'm really at .4, Hanna, even if it's wrong, I would have expected to read something closer to .1 or .2.

It just dawned on me that my LFS has one of those fancy testers that tests a whole bunch of stuff. No idea how accurate it is, but for $6, I might run a sample up to them and see what their test says.
 

jim_fitz

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possibility that the hanna is measuring ortho phosphate
whereas the ICP will measure total phosphate
 

Randy Holmes-Farley

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possibility that the hanna is measuring ortho phosphate
whereas the ICP will measure total phosphate

Yes, that's the possible but unlikely scenario I mentioned above where both could be right. It would mean a far, far higher amount of organic phosphate in the water than most folks see.
 

Dan_P

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Just got back my first ICP test on a tank that's just starting to hit a year old and started with dry rock from BRS. Most of the numbers came back fine, but a few were so far off that I have to question them. I know the idea is generally that ICP is correct and your home test is wrong, I'm just not sure here.

I've been using a Hanna Phosphate ULR tester since the beginning. Through every batch of reagent I've used, it's always returned numbers that were right in line with the most recent tests. I don't have my notes in front of me, but off the top of my head, I believe it's been in the .03-.04 range. ICP gave me a result of 133 µg/l for Phosphorus and 0.40698 mg/l for Phosphate.

The Hanna Phosphate ULR tops out at .9, so I wasn't even close to pegging it and, like I said, I've never had any issues going from one batch of reagent to the next, so I don't think the reagent is an issue.

I know the ICP tests tend to read higher (free vs bound elements or something along those lines), but from what I've read, they tend to be about double, but if I'm reading and understanding everything correctly, one of us is wrong by an order of magnitude.


While I'm here, the other ones that Triton seemed concerned with are Tin at 17, Antimony at 27, which my reading suggests this tends to be due to something electronic that's in contact with the water or something corroding. I'll check my heaters but I don't think either of them are broken or rusting. I do have one metal hose clamp on part of the return pump line that developed a white dust on it, but it's probably 18 inches above the water.
Lithium is at 397
Barium is at 46
Silicon is at 540 (but I don't have any big algae outbreaks)
In fact, here's the entire report if anyone wants to see it.
It's probably also worth noting that everything appears to be doing fine. Corals are getting bigger, fish/shrimp/snails/crabs also appear to be growing. In other words, I did the ICP test more out of curiosity (and to have a baseline) than to solve a problem.
Hanna tester is more likely to be the real number for PO4.

P, Si, and I are among the elements that seem to trip up ICP vendors.

By the way, ICP vendors do not guarantee the accuracy or precision of their results.
 
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Joe31415

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Quick update: I got a test at the LFS.
First a reminder, when I pulled the sample for the ICP test, Hanna said 446, ICP said 480. ICP said Phosphate was .4, Hanna said .04. ICP said Magnesium was 1402, Red Sea said 1340.

Not for the LFS. LFS said Alk was 7.28, Hanna said 8.2. LFS said Calcium was 383, Hanna said 468. LFS said Phosphate was .1, Hanna said .04. LFS said Nitrate was 1, Nyos and Hanna HR come back at zero.

With that said, I'm still not sure what's going on with phosphate, but I think I'll start bumping my Alk up to 9-10, that way, whether Hanna or the LFS is right, I should be safe there.
 

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