Accuracy of Phosphate ICP analysis

Mortie31

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Playing devil advocates here, I have also seen PO4 lower in my triton ICPs , but am I getting exactly 10ml in the curvette? Am I getting all of the powder out of the sachet? Am I getting all of the powder 100% dissolved? Am I getting the indexing position of the curvette lined up exactly correctly before and after shaking? Is the curvette exactly spotless? Then add in the tolerance of the checker if everything i mentioned above is perfectly done and I can see why there are differences... who is correct triton or a Hanna in my hands (and yours).. think I’d err on the side of triton.
 

Mortie31

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Playing devil advocates here, I have also seen PO4 lower in my triton ICPs , but am I getting exactly 10ml in the curvette? Am I getting all of the powder out of the sachet? Am I getting all of the powder 100% dissolved? Am I getting the indexing position of the curvette lined up exactly correctly before and after shaking? Is the curvette exactly spotless? Then add in the tolerance of the checker if everything i mentioned above is perfectly done and I can see why there are differences... who is correct triton or a Hanna in my hands (and yours).. think I’d err on the side of triton.
If you follow any of the various KH measuring devices we see similar discrepancies, with people believing the Hanna ALK checker over there KHD or alkatronic... this despite that they have calibrated there machines by weight of volume etc, yet they eyeball the 10ml sample for the Hanna and the 1ml for the reagent and then post saying the machines readings are different to there devices... let alone the inconsistency of the ALK reagents and how they change over time once opened... I personally don’t think many of us use home kits accurately enough to believe them over the machines...
 

Bramzor

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The numbers are not important. Keeping the same levels over a long time is. Living things adapt to one level. What they do not like however is having to adapt all the time because someone tries to achieve one specific number.

That is why AWC are so successful. It's a strategic and simple method to keep the numbers the same (= the values of the salt mix). You can do it while trying to aim for keeping the numbers the same by testing. I tried without AWC and just failed. You can use ICP Analysis but if you depend on it, you will have a hard time.

Just my 2 cents.
 

Dub

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Wow so for you Hanna is 3x-6x higher. Based on the fact that ICP should pick up more, all other things being equal and both tests being formed correctly, it is very likely that something is occurring in transit OR hannas just read high for some reason, but I'm not sure why that would be the case. I like @Hans-Werner post that the plastic may be absorbing some phosphate. I wish I had an ICP machine so I could do the two simultaneously without having the sample stored in the vial for 2 weeks +. Anyone have 40k+ they want to donate to the cause.........?
Why can’t one store the vial for 2 or 3 weeks and then use a Hanna test to determine if it match’s with a Hanna test done initially?
 

Bramzor

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Interested how you come to this conclusion? And what you mean by a hard time?
For one thing, if you depend on these tests for adjusting trace elements for example, you are (best case) always at least 2 weeks behind. I do love these ICP tests to check if something is way off, but not to adjust on small events. You can do that but you will be racing after numbers which can just be a testing fault (happens all the time btw).

And to come back on the phosphate thing. Isn't it that its a different kind of phosphate? Like ICP-OES tests for phosphorus and the hobby grade tests are for phosphate? Thought I read something about this long ago...
 

Mortie31

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For one thing, if you depend on these tests for adjusting trace elements for example, you are (best case) always at least 2 weeks behind. I do love these ICP tests to check if something is way off, but not to adjust on small events. You can do that but you will be racing after numbers which can just be a testing fault (happens all the time btw).

And to come back on the phosphate thing. Isn't it that its a different kind of phosphate? Like ICP-OES tests for phosphorus and the hobby grade tests are for phosphate? Thought I read something about this long ago...
I’m sorry I completely disagree, by doing monthly or bimonthly icps you can very accurately adjust trace element dosing, to match consumption by your tanks, and thousands of European reefers do exactly this. You can’t do sporadic testing and rely on it, but by being consistent and using them to check levels it is a very successful way of doing things that has been proven over several years in Europe.
 
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cjpitt80

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Why can’t one store the vial for 2 or 3 weeks and then use a Hanna test to determine if it match’s with a Hanna test done initially?
I've done that and see no difference with the standards as measured by Hanna

Playing devil advocates here, I have also seen PO4 lower in my triton ICPs , but am I getting exactly 10ml in the curvette? Am I getting all of the powder out of the sachet? Am I getting all of the powder 100% dissolved? Am I getting the indexing position of the curvette lined up exactly correctly before and after shaking? Is the curvette exactly spotless? Then add in the tolerance of the checker if everything i mentioned above is perfectly done and I can see why there are differences... who is correct triton or a Hanna in my hands (and yours).. think I’d err on the side of triton.
Playing "angel's advocate" to me, I agree with you 100% The human error factor and the fact that by Brightwell's instructions, I overdosed Lanthanum, I would be more apt to believe the Triton ICP results. Interestingly I have a 1ml pipette and can confirm that the line on the vial is not EXACTLY 10mL. It's also impossible to get all of the the powder at the sachet (going by mass) The biggest issue for me is that if the Hanna reading is unreliable, how am I supposed to track my actual PO4 levels? getting a $50 analysis weekly isn't quite in the budget for me and also means I wasted $50 on the dang Hanna meter.

And to come back on the phosphate thing. Isn't it that its a different kind of phosphate? Like ICP-OES tests for phosphorus and the hobby grade tests are for phosphate? Thought I read something about this long ago...
According to Tim @ Triton, the ICP tests for "Phosphorous, both organic and inorganic" The test results report a PO4 which I would assume is the same as the Hanna ULR Phosphate
 

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Mortie31

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The biggest issue for me is that if the Hanna reading is unreliable, how am I supposed to track my actual PO4 levels?
I believe it’s a question of “how unreliable” is acceptable, we all coped before ICP’s and I was always happy to get a reading of 30 on my ULR Hanna, my tank was happy, and I kept it at that level... i don’t think we should get hung up on comparing the 2 methods.
I will never believe anyone using a home kit can get everything spot on, even using a 1ml syringe, how do you know it holds exactly 1ml? Who calibrated it? Or was it mass printed? And can you get the meniscus at exactly the correct level every time...
 

Mortie31

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Allow me to quote Randy: "The Hanna kit tests for inorganic phosphate only"

Source: https://www.reef2reef.com/threads/h...sphorus-checker-accuracy.392577/#post-4736099
Indeed.. and that is one more reason why people shouldn’t compare the two testing methods and expect the same results.. this was discussed either earlier in this thread or on another, and what is strange is that as triton measures 2 types of phosphate you would of expected the results to be higher, but in most comparison cases the triton level is always lower.... go figure...
 

cjpitt80

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cjpitt80

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I believe it’s a question of “how unreliable” is acceptable, we all coped before ICP’s and I was always happy to get a reading of 30 on my ULR Hanna, my tank was happy, and I kept it at that level... i don’t think we should get hung up on comparing the 2 methods.
I will never believe anyone using a home kit can get everything spot on, even using a 1ml syringe, how do you know it holds exactly 1ml? Who calibrated it? Or was it mass printed? And can you get the meniscus at exactly the correct level every time...
Exactly!! LOL That's why I use a pipette from a medical research laboratory which I calibrated with molecular biology grade ultra pure water that weighs exactly 1.00gr at room temp. I am confident that my pipette does indeed hold exactly 1mL, but I just fill up the vial to the 10mL line for alk readings LOL I don't have time to fill it up 10 times....
I certainly take your point though
 

foxt

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My challenge at the moment is that i am having trouble with a few new SPS in a tank that was previously fowlr. Hanna tells me my PO4 is 0.060, Triton tells me it is 0.018. If Triton is correct, I want to bump PO4. If Hanna is correct, I will look to tweak something else.

I tend to change only one thing at a time. I will probably try increasing PO4 to 0.10 on Hanna and see what happens, but it would be great to have a higher degree if confidence in the test results
 

Mortie31

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My challenge at the moment is that i am having trouble with a few new SPS in a tank that was previously fowlr. Hanna tells me my PO4 is 0.060, Triton tells me it is 0.018. If Triton is correct, I want to bump PO4. If Hanna is correct, I will look to tweak something else.

I tend to change only one thing at a time. I will probably try increasing PO4 to 0.10 on Hanna and see what happens, but it would be great to have a higher degree if confidence in the test results
I get your dilemma, but both readings are well within limits, regarding your new sps, is every other measurement in your tank spot on? Have you placed the new sps in favourable positions, what PAR are they under? Is it right for them? Is the flow good? There are so many factors to consider and new sps are so fickle to get settled, have they deteriorated since you put them in? Or just not done anything?
 

foxt

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Thanks for the questions. I think the other parameters are where they should be: alk 8.5, NO3 5ppm, Ca 420, Mg 1400, 1.026, applicable numbers verified by Triton EXCEPT P/PO4. These monti frags started about a month ago on the bottom in moderate flow, and I have been slowly raising them to where they were in the tank I took them from - about 200PAR and moderate/hi random flow. I will just give them time, but since I have some headroom on PO4 I will bump it up a bit.

I hear ya on SPS being fickle, and I am being patient, but I am second-guessing the PO4 now, thinking it might be a little on the low side given where the NO3 is at. It would just be nice to know which it was at so I could take another variable out of the equation - Hanna at 0.060 or Triton at 0.018.

What really intrigues me though is that some people are seeing the same discrepancies I see, and others aren't. I get there are lots of variables that could be in play here, but the fact that I got the same kind of consistent discrepancy between two different water samples from two different tanks taken and sent on the same day just seems like too much of a coincidence. But who knows?
 

Mortie31

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consistent discrepancy between two different water samples from two different tanks taken and sent on the same day just seems like too much of a coincidence.
As I said earlier I get the same lower reading from Triton that you do, but I know I’m not perfect in my use of the hanna ULR kit, I can’t guarantee 10ml water volume, exact repeatable indexing of the vials in the checker, and mixing of powder is variable, so I get it near enough for me.. I’ve learnt over the last few years that 30 on my hanna will nearly always come back as 0.03 with Triton so I go with that. I just try to keep it in the ball park of 0.03 to 0.08 sometimes it will get abit higher then I just dose a little LaCl to bring it back down...
 

foxt

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As I said earlier I get the same lower reading from Triton that you do, but I know I’m not perfect in my use of the hanna ULR kit, I can’t guarantee 10ml water volume, exact repeatable indexing of the vials in the checker, and mixing of powder is variable, so I get it near enough for me.. I’ve learnt over the last few years that 30 on my hanna will nearly always come back as 0.03 with Triton so I go with that. I just try to keep it in the ball park of 0.03 to 0.08 sometimes it will get abit higher then I just dose a little LaCl to bring it back down...
I think that is what I am trying to settle on - if I get a few more results where Hanna is 3x Triton, I'll just divide by 3 whatever I get for a Hanna reading for a more realistic estimate from now on. I get very consistent results over time with the Hanna, so I am hoping I can just pick a value that is a reasonable target, and then use Hanna to track to that. I am going to experiment with these monti frags and see what happens.

Would still love to hear back from Triton (or Hanna, email out to both) about their thoughts on this.
 

cjpitt80

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Would still love to hear back from Triton (or Hanna, email out to both) about their thoughts on this.
You and me both! Hanna was "only" 7.5x higher than Triton this time, instead of 20x. So I guess I'm headed in the right direction lol
 
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