Accuracy of Phosphate ICP analysis

Dennis Cartier

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Lol, after posting about how my Hanna ULR was showing double my ICP, I was running low on re-agents and dropped by an LFS to pick some up. I was placing them on the counter and happened to ask the owner if they were the correct ones for the ULR checker (I was pretty sure they were). He examined them and found they were not the ULR ones but instead the LR ones. The spot of the shelf for the ULR ones was empty as they were out. About this time a light bulb was going off in my head. What if I had bought the wrong ones last time??

I went to a different LFS and purchased the correct ones, then I went home and compared the old box I had been using to the ULR ones. Yup, I had been using LR in the ULR checker. In that instant everything started to make sense. I had noticed a sudden jump in my daily PO4 tests. At first I had thought it was testing error, but then later, I assumed that PO4 was being released from my LR or some other place in the system. When I counted up how many packets of the LR reagent I had left, and looked back at my logs, sure enough the change in PO4 coincided with the switch to the LR instead of ULR reagents. Doh. The only silver lining is that I did not panic and do any crazy adjustments to try to correct the invalid PO4 readings.

I am looking forward to testing tomorrow morning to see what my PO4 really is.

Dennis
 
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BigJohnny

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Lol, after posting about how my Hanna ULR was showing double my ICP, I was running low on re-agents and dropped by an LFS to pick some up. I was placing them on the counter and happened to ask the owner if they were the correct ones for the ULR checker (I was pretty sure they were). He examined them and found they were not the ULR ones but instead the LR ones. The spot of the shelf for the ULR ones was empty as they were out. About this time a light bulb was going off in my head. What if I had bought the wrong ones last time??

I went to a different LFS and purchased the correct ones, then I went home and compared the old box I had been using to the ULR ones. Yup, I had been using LR in the ULR checker. In that instant everything started to make sense. I had noticed a sudden jump in my daily PO4 tests. At first I had thought it was testing error, but then later, I assumed that PO4 was being released from my LR or some other place in the system. When I counted up how many packets of the LR reagent I had left, and looked back at my logs, sure enough the change in PO4 coincided with the switch to the LR instead of ULR reagents. Doh. The only silver lining is that I did not panic and do any crazy adjustments to try to correct the invalid PO4 readings.

I am looking forward to testing tomorrow morning to see what my PO4 really is.

Dennis
Hate to burst your bubble but pretty sure they are the exact same reagent, I could be wrong though.


Edit: nvm I think I'm wrong since they have different stated accuracy levels.
 

Scorpius

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I clean my curvette prior to each use with a hard water mineral deposit remover like CLR. Doesn't hurt to get ever last bit of reside out of there for every test. I also shake the living daylights out of the cuvettte to get the powder to dissolve. The powder dissolves quicker and the occurrence of small bubbles is greatly reduced with this method. I used to mildly invert the curvette, but I always had issues with bubbles on the glass.
 

reefwiser

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To me the hardest part using the Hana checker is getting the power reagent out of the package an into the curvets[emoji3] . They need to put the reagent into a pouch like a powered drink

The thin plastic pouches would work better.
 
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Dennis Cartier

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Well I tested my PO4 this morning using the correct reagent for the ULR ... exact same reading as the day before :(

So the reagent seems to not make an appreciable difference between the 2 types of testers. Oh well, I guess I can go back to working towards lowering my PO4 because it really is as high as it appears.

Dennis
 
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BigJohnny

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Well I tested my PO4 this morning using the correct reagent for the ULR ... exact same reading as the day before :(

So the reagent seems to not make an appreciable difference between the 2 types of testers. Oh well, I guess I can go back to working towards lowering my PO4 because it really is as high as it appears.

Dennis
I thought I heard that somewhere, not sure why they have different accuracy, weird
 

ReefBum

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This didn't say anything about what your hanna results said at the time though, just that your triton phosphate levels went down. Do you remember how much higher it was?
Ok, here are my Hanna results versus ICP:

9/8/17: Hanna .05 versus .02 for ICP
12/19/17: Hanna .04 versus .01 for ICP
1/28/18: Hanna .14 versus .01 for ICP

According to Hanna, it appeared I didn't have a problem with low phosphates.
 

Reefltx

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Ok, here are my Hanna results versus ICP:

9/8/17: Hanna .05 versus .02 for ICP
12/19/17: Hanna .04 versus .01 for ICP
1/28/18: Hanna .14 versus .01 for ICP

According to Hanna, it appeared I didn't have a problem with low phosphates.
I’ve noticed the same.

According to triton/ati my po4 always tested lower than my Hanna.

I find it funny that we are having to dose nutrients in our tank instead of the opposite nowadays.
 
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BigJohnny

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Ok, here are my Hanna results versus ICP:

9/8/17: Hanna .05 versus .02 for ICP
12/19/17: Hanna .04 versus .01 for ICP
1/28/18: Hanna .14 versus .01 for ICP

According to Hanna, it appeared I didn't have a problem with low phosphates.
Thanks. Very interesting and my experience as well. Thanks
 
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Rick Mathew

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Curious because my Hanna ulr phosphorus shows 2-3x more on average than icp. I stopped using it though because my experience with hanna is that they are consistent but accuracy/reagents can vary so it's better for relative measurements, and that assumes perform the test perfectly and clean the tubes perfectly.

Haven't tried another hobby kit recently as I don't and always assumed the ICP was more accurate. Thoughts? Any reason to think the phosphate is being consumed by bacteria in transit or something weird like that, resulting in the much lower reading?

Thanks
Revising for more help. I've had TERRIBLE issues with this. My Hanna reads TWENTY times higher than Triton. 0.14ppm vs .007ppm Ordered NIST traceable reference standard and Hanna reads well within 5% range.... I'm confused https://www.reef2reef.com/threads/triton-testing-and-nutrients.634505/
I have had very good results with the Hanna Checker and have also seen this discrepancy between my Checker results and ICP test results....I have recently been sending my water test samples to 3 different ICP testing services...Mainly to see what variation there is between them...as well as from my test results

Here the results of the last 4 sets of tests of the PO4 in ppm

My Results Hanna Checker ICI #1 ICP # 2 ICP# 3

.037 .031 .025 Not measured
.025 .013 .019 .031
.037 .040 .031 .092
.000 .017 .030 .092

For the most part my test results are close to or within range of the ICP results with the exception of ICP# 3... I am not going draw any conclusions as of yet...I am going to continue this for 6 more test cycles (ever 2 months)...When looking at the results of the other parameters...Not just PO4 there is some large variations in the results between the different ICP testing providers...The question is always "Which on is Correct"?

As previously mentioned in this thread there might be an issue with the sample transit time and conditions that have an impact on the results...You might set up an experiment in which you take several samples at the same time....say 3-5...and store them in different environment for the period equivalent to the shipping time of the sample sent to ICP provider. Do an initial test the day the samples are taken then retest the stored samples...I would test them every 2-3 days or so just to see if there is a trend, but at least 2 times during this period....might give some insight as to what is happening...Just an Idea
 

cjpitt80

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I have had very good results with the Hanna Checker and have also seen this discrepancy between my Checker results and ICP test results....I have recently been sending my water test samples to 3 different ICP testing services...Mainly to see what variation there is between them...as well as from my test results

Here the results of the last 4 sets of tests of the PO4 in ppm

My Results Hanna Checker ICI #1 ICP # 2 ICP# 3

.037 .031 .025 Not measured
.025 .013 .019 .031
.037 .040 .031 .092
.000 .017 .030 .092

For the most part my test results are close to or within range of the ICP results with the exception of ICP# 3... I am not going draw any conclusions as of yet...I am going to continue this for 6 more test cycles (ever 2 months)...When looking at the results of the other parameters...Not just PO4 there is some large variations in the results between the different ICP testing providers...The question is always "Which on is Correct"?

As previously mentioned in this thread there might be an issue with the sample transit time and conditions that have an impact on the results...You might set up an experiment in which you take several samples at the same time....say 3-5...and store them in different environment for the period equivalent to the shipping time of the sample sent to ICP provider. Do an initial test the day the samples are taken then retest the stored samples...I would test them every 2-3 days or so just to see if there is a trend, but at least 2 times during this period....might give some insight as to what is happening...Just an Idea
Yeah. Seems like I need to do some serious testing. I'm either high or low, but don't know which. There is definitely an imbalance somewhere. My euphyllia are pulling away [emoji35]. Can't grow ANY SPS... possibly could be the transit time, 9 days for last turn around time
 

Rick Mathew

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Yeah. Seems like I need to do some serious testing. I'm either high or low, but don't know which. There is definitely an imbalance somewhere. My euphyllia are pulling away
. Can't grow ANY SPS... possibly could be the transit time, 9 days for last turn around time
Yeah. Seems like I need to do some serious testing. I'm either high or low, but don't know which. There is definitely an imbalance somewhere. My euphyllia are pulling away
. Can't grow ANY SPS... possibly could be the transit time, 9 days for last turn around time
So...Something else to consider. Could it be something else is causing the problem with the tank and the PO4 level is not the issue. .14 ppm is not is not excessively high...I on occasion venture into this level but don't have the kind of results you are experiencing. The fact that you checked the Checker with a NIST Standard and got good results would tell me that the checker is accurate. Are you doing any kind of carbon dosing? I use NOPOX to help control the NO3/PO4 ...I would also start looking at some of the other factors...pH Salinity, Alkalinity etc. I assume your TRITON results did not highlight any other issues.
 

IslandLifeReef

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My results with ATI ICP were 10.36 ppb of Phosphorus. Hanna check had 12 ppb Phosphorus. Water taken at the same time. I'd say that those results are practically identical considering the error of a home test kit.
 

cjpitt80

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So...Something else to consider. Could it be something else is causing the problem with the tank and the PO4 level is not the issue. .14 ppm is not is not excessively high...I on occasion venture into this level but don't have the kind of results you are experiencing. The fact that you checked the Checker with a NIST Standard and got good results would tell me that the checker is accurate. Are you doing any kind of carbon dosing? I use NOPOX to help control the NO3/PO4 ...I would also start looking at some of the other factors...pH Salinity, Alkalinity etc. I assume your TRITON results did not highlight any other issues.
Certainly could be something else, because though I've been at this over 18months, I am faaaaaaaaaaaaar from an expert or experienced. I do no carbon dosing. I don't dose anything but Triton Core 7 other methods. I WAS dosing KNO3 until I got Nitrates to 5ppm where they have been for about a month now. Obviously I WAS dosing the Brightwelll stuff, but I've stopped since 7/24. I have chaeto in fuge. pH is always around 7.9/8.1 night/day. My ATO keeps salinity at 1.025. Alk stays between 8.4-8.7 dKH (not daily swing, but if I check it it's between there.) Temp is 80-82 range (I know a little warm, but been that way since tank was started). Other parameters are on the ICP result. Really only major thing changed has been my attempts to lower PO4. The frogspawn I lost had been in the tank over a year and not recently moved. Same with the octospawn heads I lost. I was able to keep (and GROW) a plating red Monti Cap for about a year. I lost it back in mid May to what I suspect was an Alk spike. The euphyllia and acans were unaffected. No major livestock additions since adding a Bristle tooth tang 1st week of June. Not sure what's going on now, but running carbon, doing weekly 15% water changes and praying....
 

Rick Mathew

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Certainly could be something else, because though I've been at this over 18months, I am faaaaaaaaaaaaar from an expert or experienced. I do no carbon dosing. I don't dose anything but Triton Core 7 other methods. I WAS dosing KNO3 until I got Nitrates to 5ppm where they have been for about a month now. Obviously I WAS dosing the Brightwelll stuff, but I've stopped since 7/24. I have chaeto in fuge. pH is always around 7.9/8.1 night/day. My ATO keeps salinity at 1.025. Alk stays between 8.4-8.7 dKH (not daily swing, but if I check it it's between there.) Temp is 80-82 range (I know a little warm, but been that way since tank was started). Other parameters are on the ICP result. Really only major thing changed has been my attempts to lower PO4. The frogspawn I lost had been in the tank over a year and not recently moved. Same with the octospawn heads I lost. I was able to keep (and GROW) a plating red Monti Cap for about a year. I lost it back in mid May to what I suspect was an Alk spike. The euphyllia and acans were unaffected. No major livestock additions since adding a Bristle tooth tang 1st week of June. Not sure what's going on now, but running carbon, doing weekly 15% water changes and praying....
Quick question what are you using to measure your Specific Gravity?
 

Rick Mathew

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Certainly could be something else, because though I've been at this over 18months, I am faaaaaaaaaaaaar from an expert or experienced. I do no carbon dosing. I don't dose anything but Triton Core 7 other methods. I WAS dosing KNO3 until I got Nitrates to 5ppm where they have been for about a month now. Obviously I WAS dosing the Brightwelll stuff, but I've stopped since 7/24. I have chaeto in fuge. pH is always around 7.9/8.1 night/day. My ATO keeps salinity at 1.025. Alk stays between 8.4-8.7 dKH (not daily swing, but if I check it it's between there.) Temp is 80-82 range (I know a little warm, but been that way since tank was started). Other parameters are on the ICP result. Really only major thing changed has been my attempts to lower PO4. The frogspawn I lost had been in the tank over a year and not recently moved. Same with the octospawn heads I lost. I was able to keep (and GROW) a plating red Monti Cap for about a year. I lost it back in mid May to what I suspect was an Alk spike. The euphyllia and acans were unaffected. No major livestock additions since adding a Bristle tooth tang 1st week of June. Not sure what's going on now, but running carbon, doing weekly 15% water changes and praying....
When you do your weekly water changes are you doing it all at one time or spread over several days?
 

cjpitt80

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When you do your weekly water changes are you doing it all at one time or spread over several days?
All at one time. Make salt. Let it mix for a full day or so. Check salinity. Recheck. Change. I use a standard 13gal trash can. I have a 75gal with 29gal sump. About 80 gal total water volume, so I figure about 15% WC or so. Did my 2nd one this past weekend
 

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