SAMPLE STORAGE AND ITS IMPACT ON PHOSPHATE MEASUREMENT

[Dan_P]

Ive had that same concern about trace elements since these businesses started.

If good experiments could be designed, we could just put the vendors to the test. It would be a little pricey, so, the experiments and controls would have to be exquisitely designed

@Rick Mathew has recently invited me and @taricha to explore this rabbit hole with him (To be honest I asked if I might have peek). I am sure there will be ideas on how we might try to do this in a future post along with the question of how to involve the vendors.

 

[Anchor]

My worthless 2 cents worth...

I found a problem that the average reefer testing PO4 might want to address while using the Hanna ULR phosphate checker.

I bought 2 new vials/cuvettes for testing with my Hanna checkers.
I used one with my KH checker and the other on the Phosphate.
I left them sit for 3 days still filled with the tested sample
I went to test again on the 3rd day, rinsed both in tap and DI water 3 times each as is my routine.
Rinsed both with tank water 3 times each, as is routine, at least for most chemists I know.
I then filled each with my tank water sample and tested.
KH came out as expected but the PO4 dropped to 0, down from .08. This was unexpected so I tested again and again got 0, using the same cuvette and prepped as above. Now, knowing nothing was done to the tank to have given me that drop in those 3 days, I started thinking something wrong with the tester, the cuvette or my method. I started with the cuvette and noticed a heavy film on the inside of it. I then used my mini bottle brush and cleaned it well with Iso and the brush and then rinsed several times with DI water. THe cuvette cleared up.. I let it dry for several hous and was still clean so tested again and got my expected 0.07 result.

I guess my add to this discussion is
1. Don't leave samples in the cuvettes for days.
2. Brush clean and not just rinse them before and or after testing.
3. Cleanliness is next to chemicalliness (meh, I tried to be funny)

As a former chem worker myself I should have known all this but not all reefers do. Whether the resulting changes you are seeing is due to biofilm or a difference in chemical make-up of what is in tank water vs. more purified, prepared standards I am unable to speculate on. But, a sample of even dirty freshwater tends to floc or film up over even short periods of time, in my experience (former environmental lab rat) and as previously stated by someone else, most samples taken for lab analysis were acid treated, depending on the type of test that sample was to be tested for.

As Hanna checkers use glass cuvettes, I know that glass tended to attract a biofilm based on experience from the field.
And a film on the glass will lower the test reading.

Did I over state an obvious point made earlier?

 

[Ehsan@triton]

Great explanation, but if the sample requires several days of transport before it is analyzed, the phosphorous, orthophosphate or organophosphate, can be assimilated by microorganisms. If those microorganisms are attached to the surface of the sample container, will the assimilated phosphorous be detected?

In answer to the above, this is something that I was concerned about over 8 years ago when developing the ICP methods for testing marine aquarium water.
Based on this concern TRITON conducted a lot of research and testing to determine the impact of bio-activity in a posted sample.
We adapted our methodology to ensure that measured phosphorus results were consistent and valuable regardless of the time taken for transport of the sample.
Adaptions to our methodology, which is proprietary, is how we addressed these concerns and, as Lasse mentioned earlier, this can be done is a variety of ways, such as acidification.
Delivering a better, more applicable, P reading was not difficult as low range home testing kits (which includes photometers) have a much wider error range.

One more thing that I would like to mention here is that we initially did the same thing for Nitrate (NO3).
Our concerns with bio-activity of the sample during transport led us to conduct testing and research into whether we could provide a valuable reading for this commonly tested molecule.
Back then we were using HPLC for this purpose.
Unfortunately, regardless of how we adapted our methodology of the HPLC (not ICP) protocol, we were unable to provide consistent and satisfactory readings for NO3 and, as a result, do not offer results for this water parameter.

Ive had that same concern about trace elements since these businesses started.

In addition to this there are many more problems that are associated with transit time with water samples that you may not even be aware of.

For example Mercury (Hg). Even without bio-activity in the sample vial this element can stick to the surface as can, maybe not to the same extent, Tin (Sn). Chloride, not being a trace element, can be affected by organic carbon when testing with an ICP.

These are just some examples of the challenges that TRITON has identified and overcome through years of research and testing.
When you buy an ICP machine the company that build it can tell you how to test seawater but not how to address the challenges associated with transit times and the other aquarium specific problems that are commonly faced.
This is why we say that just because you own an ICP-OES machine doesn’t mean you know how to test aquarium water and make the results applicable and valuable to the modern aquarist.

 

[Julian@Triton]

SAMPLE STORAGE AND ITS IMPACT ON PHOSPHATE MEASUREMENT​

In a discussion on R2R @BigJohnny posed a question about why his Hanna ULR Phosphorous test results were significantly lower (2-3 times) than his ICP test results…. Here is a link to the discussion

Accuracy of Phosphate ICP analysis

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...

www.reef2reef.com

One of the possible reasons that were proposed was the potential impact of sample transit time and could that have an impact on the results of the ICP test. So I set up a series of experiments to test the hypothecs. At first it was a simple one time experiment in which I took a large sample and measured the dKH, NO3, PO4 and Iodine Levels on the initial sampling. Each was measured 3 times and an average value calculated. The dKH was measured with the Hanna Checker. The Nitrate was measured using the test I developed using the Hanna HI-764 (link to details--- https://www.reef2reef.com/ams/test-meter-for-testing-nitrates.599/ )

The PO4 was tested using the Hanna HI-736 Phosphorous ULR Checker and the Iodine was tested using the method I developed ( link to details https://www.reef2reef.com/ams/using-hanna-checker-hi-707-to-test-for-iodine.743/ )

I took the rest of the remaining sample and split into two sample sets. The first one I stored inside in a controlled environment. The second one I placed in the glove compartment of my car…Uncontrolled environment. I live in Florida where we can get cool nights and hot days so there was some variability. I then tested the samples on day 5, day 10, and day 19…Below is the results. (CHARTS 1-4)

CHART 1

CHART 2

CHART 3

CHART 4
​

As you can see from the charts the PO4 and Iodine measurements changed quite significantly. The dKH and NO3 measurements stay within the expected error range over the testing period.

From these results a question arose as to whether or not the composition of the container could have an impact on the results. A second experiment was conducted using containers made of different materials…Glass, Polypropylene, High Density Polyethylene, Polyethylene, PET, Poly-carbonate and Polystyrene. I chose to test only the PO4 because it had the biggest change over time as well as this was the parameter that posed the question. In addition the measurements were taken using two different Hanna Testing Meters... the HI-736 ULR Phosphorous Meter and the HI-774 ULR Phosphate Meter. The tests were replicated at least 2 times for confirmation some were done as many as 4 times. There are a lot of charts (23) resulting from this set of experiments that I won’t include here, but if you are interested I can send you the charts.

The initial findings indicated that there were measurable differences between the different containers, with glass and PET giving the best results. Then @Dan_P raised the question could the Surface Area to Volume ratio (SA/V) be a factor given that the containers were of different sizes. Sure enough his hunch was correct. The containers with the highest SA/V ratio had the worst results. This initiated a third round of experiments using containers with equivalent SA/V ratios. I chose to use the actual sample tubes provided by the ICP vendor that are made from Polypropylene (PP) and glass sample tubes with the same volume and dimensions thus giving the same SA/V ratio. These tests were also done in duplicate. The results are below. (CHARTS 5 & 6)

CHART 5

CHART 6
​

As you can see both the PP Sample Tubes as well as the Glass Sample Tubes showed a decrease in the measured PO4 with both testers. This is a clear indicator the samples are not stable during shipment & or storage at least with respect to PO4. as tested with the Hanna Checkers

At this point a question was posed by as to whether this was due to Bio-Activity or purely a chemical reaction. I had remembered reading that one of the ICP vendors had tested the question of storage stability using a HACH standard solution and testing it over several days. They reported that the measurement was stable over the storage period. I decided to replicate this experiment.

I made up a PO4 standard at .06 ppm using salt water at 35ppt made with RODI water and reagent grade Sodium Chloride and a HACH Standard. The thinking was that this should represent a Bio-Inactive sample. The same test protocol that was used for the tank sample was used. I chose two different containers, glass and a HDPE, the results are below: (CHARTS 7 & 8)

CHART 7

CHART 8​

The test results indicated that although there was a change over the storage period the results were within testing error and did not show the significant change found in the tank samples that were Bio-Active.

After reviewing the test procedure of the HACH Standard experiment I had some question as to whether the containers were completely free of any Bio material. I did a repeat of the test after sterilizing both containers. Results are below: (CHARTS 9 & 10)

CHART 9

CHART 10
​

The above results replicate the results of the ICP vendor. Using the HACH Standard the measurements remain relatively stable over the sample storage period.

This would be an indicator that the instability of the PO4 is related to the Bio-Activity of the tank samples.

One hypothesis is that the Bio-Active samples from the tank are forming a thin bio-film on the sides of the containers that over time adsorb the organic phosphate their by reducing the amount of PO4 in the water being tested. This is only one of several possible explanations yet to be explored.

An additional experiment was set up to see it ‘Pre-Conditioning” the container might be helpful. The thought was by doing this the film would be formed and the tubes would be “conditioned” and the next sample placed in the tube would not undergo the “film forming” because the film was already there.

The PP sample tubes were filled with tank water and allowed to set for 12 days. An initial measurement was taken (Day 0) and then a second measurement on day 12. The tubes were then re-filled with a second batch of tank water without rinsing out the tubes. The second batch was then tested according to the standard test protocol. (Store samples and test on day 0, 3 & 6 and test with the 2 Hanna Checkers). The results are below: (Charts 11 & 12)

CHART 11

CHART 12
​

These test result indicate the “conditioning” under this set of parameters does not appreciably reduce the effect of loss of PO4 over time: That being said, there are additional experiments that by changing the parameters could define a set of conditions where “pre-conditioning” the container could prove to be successful. These experiments are yet to be completed.

It also could be that the hypotheses is incorrect and there is some other mechanism causing this…Bacteria interaction…some type of chelation process….and who know what else….Most of this is way above my pay grade, but many of you out there in R2R Family have the skills, knowledge and ability to contribute ideas.

SOME INITIAL CONCLUSIONS:

• Samples stored in high SA/V containers (Sample Tubes) are not stable over time with respect to PO4 measurement when tested with Hanna Checkers.
• The problem is associated with tank water (Bio-Active) and does not show up with “sterile” samples made with PO4 standards.
• The type of container does not appear to make a difference. The SA/V Ratio appears to be the controlling factor.

SOME INITIAL SPECULATIONS:

• This could be a possible explanation of why a number of Reefers get significantly different results from there testing protocol and ICP results when testing PO4.
• There could be other test parameters that are affected by this issue.
• A different sampling protocol may be necessary to insure better ICP test results related to some test perimeters.

Well that is about the long and the short of it at this point. The work is continuing and I will provide updates as they are completed. There are so many “Rabbit Holes” to this project! I have several questions yet to be explored….

• Does the initial PO4 level change the outcome?
• Are there other parameters to be concerned about? Evidence says Iodine might be an issue…
• What is the effect of temperature; would keeping the sample cold reduce the problem?
• Is there a critical Surface Area to Volume Ration where the problem is reduce or eliminated and what is it?
• Why are there some cases where the ICP results closely match the results obtained by the Hanna Checkers and yet there are other times they are vastly different (2-3 times)?

And I am sure many of you will have some great questions to be answered.


Thanks again to @Dan_P and @taricha for their help and guidance in this project...What an awesome family this R2R group is!!
One thing is for sure BRS is happy about this project. With over 200 individual tests and more to come their sales of Checker Reagent is benefiting greatly!

​

I am confused, which happens more and more often these days as I get on in years

Your results show that over time the PO4 values in the water sample could/should drop due to bio-activity while most people report that their Hanna Checker test results are significantly lower (2-3 times) than the value reported by ICP lab testing after the time spent in transit. This does not seem to make any sense based on your findings?

 

[Rick Mathew]

I am confused, which happens more and more often these days as I get on in years

Your results show that over time the PO4 values in the water sample could/should drop due to bio-activity while most people report that their Hanna Checker test results are significantly lower (2-3 times) than the value reported by ICP lab testing after the time spent in transit. This does not seem to make any sense based on your findings?

I for sure know about being more and more confused

So actually my experiment was prompted by a question asked by @BigJohnny (here https://www.reef2reef.com/threads/accuracy-of-phosphate-icp-analysis.381738/) in which he stated "Curious because my Hanna ulr phosphorus shows 2-3x more on average than icp." (post # 1).

In post # 3 he reported his numbers..
Hanna- 61 ppb Phosphorous, .19 ppm PO4
Triton- 22 ug/l Phosphorous, .07 mg/l PO4

And in post # 50
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

So each time his Hanna Checker results were greater the the reported ICP results. I Have been submitting my tank water to be tested for several years now, both ICP testing as well as Non-ICP Testing. Last year I sent the same water sample to 3 different ICP vendors for testing....So I thought I would have a look at my data set for PO4 measurements comparing my results with the outside testing results...This is the data in the table below

As you can see the general trend is the same as @BigJohnny observed...My results tended to be higher then the outside test results...Both ICP as well as standard water testing...

I first looked at was there some systematic error in my testing protocol that caused this. I used prepared standards and did a Gage R&R on the test protocol and did not find any procedural issues that would cause these larger discrepancies...So I followed an idea proposed in the thread that "something could be happening in transit"....Independent of my tests or the outside vendors test...That is to say are we actually testing "different" samples

rick

 

[Julian@Triton]

Thanks Rick. I can see in the discussion that his readings were indeed higher. Maybe you need to change your wording at the start of your post as it currently indicates the opposite as I read it:

“In a discussion on R2R @BigJohnny posed a question about why his Hanna ULR Phosphorous test results were significantly lower (2-3 times) than his ICP test results….”

Regardless, the most common question I receive from customers is “Why are my Hanna Phosphorus test results significantly lower than my recent ICP test results?” which is in contrast to your, and @BigJohnny’s experience. The question is so commonly asked that we felt the need to address it in this thread posted a couple of months ago:

What an ICP-OES machine CANNOT test

What an ICP-OES machine CANNOT test As the company that developed the method for sea water analysis and making broadband testing available to aquarists, we at TRITON often get asked what an ICP-OES machine CAN test. These days it is getting more and more confusing with the proliferation of...

www.reef2reef.com

As you can see, Ehsan also replied to your post and I am keen to hear your thoughts on his response.

 

[Rick Mathew]

Thanks Rick. I can see in the discussion that his readings were indeed higher. Maybe you need to change your wording at the start of your post as it currently indicates the opposite as I read it:

“In a discussion on R2R @BigJohnny posed a question about why his Hanna ULR Phosphorous test results were significantly lower (2-3 times) than his ICP test results….”

Regardless, the most common question I receive from customers is “Why are my Hanna Phosphorus test results significantly lower than my recent ICP test results?” which is in contrast to your, and @BigJohnny’s experience.

As you can see, Ehsan also replied to your post and I am keen to hear your thoughts on his response.

Thanks for the catch....Told you I was easily confused....Am I coming or going


Make your day a great one!!

 

[Rick Mathew]

Thanks Rick. I can see in the discussion that his readings were indeed higher. Maybe you need to change your wording at the start of your post as it currently indicates the opposite as I read it:

“In a discussion on R2R @BigJohnny posed a question about why his Hanna ULR Phosphorous test results were significantly lower (2-3 times) than his ICP test results….”

Regardless, the most common question I receive from customers is “Why are my Hanna Phosphorus test results significantly lower than my recent ICP test results?” which is in contrast to your, and @BigJohnny’s experience. The question is so commonly asked that we felt the need to address it in this thread posted a couple of months ago:

What an ICP-OES machine CANNOT test

What an ICP-OES machine CANNOT test As the company that developed the method for sea water analysis and making broadband testing available to aquarists, we at TRITON often get asked what an ICP-OES machine CAN test. These days it is getting more and more confusing with the proliferation of...

www.reef2reef.com

As you can see, Ehsan also replied to your post and I am keen to hear your thoughts on his response.

Very nice write up. It is a good idea to explain what an instrument can not do. It provides a much more complete picture of capabilities...Thank you

I use your testing services regularly and am very pleased with it...I especially like that you significantly sped up the turn around time for samples!! Awesome...Thank you!

So with regards to the PO4 measurement does the picture below essentially describe what is being said with regards to the differences between a hobby grade test kit and ICP measurements..(I do much better with pictures

The more of the organic phosphate present the lower the correlation in the two readings

From your comments above on the most common question, I would then suspect that many reef systems have a predominance of organic phosphate and not so much reactive phosphate....correct?



Thanks for taking the time to help me understand this I appreciate it.

 

[Lasse]

As I said before - my problem have been that my Hanna HI-774 all the times report higher PO4 values that my Triton test do. It is a new meter bought in september last year. I wash my tubes with citric acid every two weeks. I calibrate two tubes to show the same zero value - using one for zero and one for the samples. after completed reaction time - I do a serie of tests with first zeroing (the zero sample) and than analysing (sample) I repeat this readings up to ten times. Mostly I get results that swing around an average value plus/minus 0,02 ppm. In the fall I read around 0,08 - 0.12 all the time. The corals did not grow very well. I run GFO and AL99 in attempts to pres it down to around 0.06 (my wanted value) Did not succeed - the Triton test that I send in in late august show 0.03 ppm PO4. I bought this Hanna in order to manage the PO4. When I start to test with it - I get 0.1 - 0.12. Try to press it down as I say above. In late november - next Triton show 0.018 ppm PO4. My Hanna show 0.1 ppm. Start to dose PO4. Corals start to grow and thing looks very much better. in late january - my Triton test show 0,036 and my Hanna show 0.12. I conclude that the Hanna show around 0.08 above my real PO4 content. Things have developed well and the last Triton (a week ago) show 0.06 ppm. My Hanna had run wild this time - I had forget to clean the tubes with acid. Exactly there I want to be.

A friend of mine have done a lot of testes with different brands and compared them with Triton tests. Surprisingly for me - he recommend Red Sea Pro PO4 test. And I know how meticulous and careful he is with everything he does - I decided to buy such a test. Today I get it and I did a comparison with this test and my Hanna (with acid cleaned tubes) and the result was rather thoughtful. Red sea 0.08 and an average of 6 readings (with the same sample and same zero sample) with Hanna give me 0.16 ppm. This was the first analyse I did with Red Sea Pro PO4 and I know of experiences that I need 15 - 20 tests in order to learn the methods I do for the first time. We will see in a week or two if I can trust this test instead of Hanna.

I can see another advantage with this test. I have to compare colours with my own eyes and in different lights (they recommend 6500 K) I know that my eyes can trick me and understand that the value is somewhere around the value I read. When I read the digits in the Hanna window - my brain trick me to think that this is the very real value because it is digits - not colours.

Sincerely Lasse

 

[Rick Mathew]

As I said before - my problem have been that my Hanna HI-774 all the times report higher PO4 values that my Triton test do. It is a new meter bought in september last year. I wash my tubes with citric acid every two weeks. I calibrate two tubes to show the same zero value - using one for zero and one for the samples. after completed reaction time - I do a serie of tests with first zeroing (the zero sample) and than analysing (sample) I repeat this readings up to ten times. Mostly I get results that swing around an average value plus/minus 0,02 ppm. In the fall I read around 0,08 - 0.12 all the time. The corals did not grow very well. I run GFO and AL99 in attempts to pres it down to around 0.06 (my wanted value) Did not succeed - the Triton test that I send in in late august show 0.03 ppm PO4. I bought this Hanna in order to manage the PO4. When I start to test with it - I get 0.1 - 0.12. Try to press it down as I say above. In late november - next Triton show 0.018 ppm PO4. My Hanna show 0.1 ppm. Start to dose PO4. Corals start to grow and thing looks very much better. in late january - my Triton test show 0,036 and my Hanna show 0.12. I conclude that the Hanna show around 0.08 above my real PO4 content. Things have developed well and the last Triton (a week ago) show 0.06 ppm. My Hanna had run wild this time - I had forget to clean the tubes with acid. Exactly there I want to be.

A friend of mine have done a lot of testes with different brands and compared them with Triton tests. Surprisingly for me - he recommend Red Sea Pro PO4 test. And I know how meticulous and careful he is with everything he does - I decided to buy such a test. Today I get it and I did a comparison with this test and my Hanna (with acid cleaned tubes) and the result was rather thoughtful. Red sea 0.08 and an average of 6 readings (with the same sample and same zero sample) with Hanna give me 0.16 ppm. This was the first analyse I did with Red Sea Pro PO4 and I know of experiences that I need 15 - 20 tests in order to learn the methods I do for the first time. We will see in a week or two if I can trust this test instead of Hanna.

I can see another advantage with this test. I have to compare colours with my own eyes and in different lights (they recommend 6500 K) I know that my eyes can trick me and understand that the value is somewhere around the value I read. When I read the digits in the Hanna window - my brain trick me to think that this is the very real value because it is digits - not colours.

Sincerely Lasse

Wow that is a big difference between the Red Sea Test and the 774...I have noticed that my 774 generally reads higher than my HI-736 which is the one I use most of the time...usually .02 higher in general...That is good information on the Red Sea...I think I will check it out..

I know exactly what you mean about if it is "digital" it must be true!.... I have had that very conversation with a number of people attending the colour physics class I teach at the University of Akron...Do you believe your eyes or "the number", one of them is not telling the truth!

Thanks for sharing

Regards
rick

 

[Dan_P]

As I said before - my problem have been that my Hanna HI-774 all the times report higher PO4 values that my Triton test do. It is a new meter bought in september last year. I wash my tubes with citric acid every two weeks. I calibrate two tubes to show the same zero value - using one for zero and one for the samples. after completed reaction time - I do a serie of tests with first zeroing (the zero sample) and than analysing (sample) I repeat this readings up to ten times. Mostly I get results that swing around an average value plus/minus 0,02 ppm. In the fall I read around 0,08 - 0.12 all the time. The corals did not grow very well. I run GFO and AL99 in attempts to pres it down to around 0.06 (my wanted value) Did not succeed - the Triton test that I send in in late august show 0.03 ppm PO4. I bought this Hanna in order to manage the PO4. When I start to test with it - I get 0.1 - 0.12. Try to press it down as I say above. In late november - next Triton show 0.018 ppm PO4. My Hanna show 0.1 ppm. Start to dose PO4. Corals start to grow and thing looks very much better. in late january - my Triton test show 0,036 and my Hanna show 0.12. I conclude that the Hanna show around 0.08 above my real PO4 content. Things have developed well and the last Triton (a week ago) show 0.06 ppm. My Hanna had run wild this time - I had forget to clean the tubes with acid. Exactly there I want to be.

A friend of mine have done a lot of testes with different brands and compared them with Triton tests. Surprisingly for me - he recommend Red Sea Pro PO4 test. And I know how meticulous and careful he is with everything he does - I decided to buy such a test. Today I get it and I did a comparison with this test and my Hanna (with acid cleaned tubes) and the result was rather thoughtful. Red sea 0.08 and an average of 6 readings (with the same sample and same zero sample) with Hanna give me 0.16 ppm. This was the first analyse I did with Red Sea Pro PO4 and I know of experiences that I need 15 - 20 tests in order to learn the methods I do for the first time. We will see in a week or two if I can trust this test instead of Hanna.

I can see another advantage with this test. I have to compare colours with my own eyes and in different lights (they recommend 6500 K) I know that my eyes can trick me and understand that the value is somewhere around the value I read. When I read the digits in the Hanna window - my brain trick me to think that this is the very real value because it is digits - not colours.

Sincerely Lasse

@Lasse are you comparing results of Red Sea visual color matching to Hanna?

 

[Dan_P]

Wow that is a big difference between the Red Sea Test and the 774...I have noticed that my 774 generally reads higher than my HI-736 which is the one I use most of the time...usually .02 higher in general...That is good information on the Red Sea...I think I will check it out..

I know exactly what you mean about if it is "digital" it must be true!.... I have had that very conversation with a number of people attending the colour physics class I teach at the University of Akron...Do you believe your eyes or "the number", one of them is not telling the truth!

Thanks for sharing

Regards
rick

@Rick Mathew and @taricha, you know what this means? Red Sea Pro PO4 chemistry needs to go into a Hanna photometer and a spectrophotometer for a head to head challenge. My money is on the two tests are equivalent once you remove human vision factor.

 

[Rick Mathew]

@Rick Mathew and @taricha, you know what this means? Red Sea Pro PO4 chemistry needs to go into a Hanna photometer and a spectrophotometer for a head to head challenge. My money is on the two tests are equivalent once you remove human vision factor.

Already ordered it.....Shoot Out at the "PO4" Corral

 

[taricha]

@Rick Mathew and @taricha, you know what this means? Red Sea Pro PO4 chemistry needs to go into a Hanna photometer and a spectrophotometer for a head to head challenge. My money is on the two tests are equivalent once you remove human vision factor.

I'm game, too. I'll order a Red Sea PO4 kit tomorrow.

 

[Lasse]

@Lasse are you comparing results of Red Sea visual color matching to Hanna?

Yes I use the Red Sea pro test as it should with colour comparison with my own eyes.

And the result (if it will be stable) is only valid for my Hi-774. IMO - if my Hi-774 not give me the right result - it is probably not a function of bad reaction chemicals - it is more plausible that it is a function of the meter - with other words - a technical problem. My first Red Sea pro test show a result rather similar to my Triton result 2 weeks ago. The last 4 Triton tests - my Hanna test meters have shown a result 0.08 ppm above Triton result with one exception there the Hanna show figures far away from Triton result. One of the > 0.08 tests was done with my old Hi-713 - and was the reason why I bought a new one.

I will do a couple of test the following days and see whats happen but the right answer I will not get before I can test both against a Triton analyse. I do Triton around every three months.

But - it is important to stress that this is valid for my meter - it does not mean that it is valid for all Hanna´s out there. In my case - I trust the results from Triton but if I only had test between Red Sea Pro and Hi-774 - I probably had state that the Red Sea Pro can´t be trusted. In my case - I have - before my test with Red Sea Pro - two indications that I had to trust Triton over my Hi-774. Knowledge about the Triton Method of ICP testing and my IRL observations of my aquarium. Maybe - the Red Sea Pro PO4 test will give me a third indication of not trust MY Hi-774. If I can show that the difference between Red Sea Pro and my Hi-774 is stable and the Red Sea Pro is showing close to Triton - it does not matter what I read on my Hi-774 - it is only a subtraction to do in order to get a valid result. But my test serie of more than 10 readings with the same zero and the same sample show that the result many time are plus/minus 0.02 around a average value. it is in order with Hannas own figures of accuracy. A second test this morning show concentration between 0.08 and 0.12 with Red Sea Pro and a an average of 0,18 with mine Hi-774. See attached excel file.

The photos have been taken with my Olympus TG-6, microscope - gaffling and with adjusted white balance. In next session (I will update the excel file) I will take with photos of all concentrations including zero.

Sincerely Lasse

 

[taricha]

my problem have been that my Hanna HI-774 all the times report higher PO4 values that my Triton test do. It is a new meter bought in september last year. I wash my tubes with citric acid every two weeks.

FYI, after recently doing some tests with higher-than-reef PO4 levels, my tubes started accumulating blue stain.
Citric acid overnight soaks did nothing to reduce the blue.
but a drop of bleach+soap spray product turned the tubes crystal clear again.

 

[Dan_P]

Yes I use the Red Sea pro test as it should with colour comparison with my own eyes.

And the result (if it will be stable) is only valid for my Hi-774. IMO - if my Hi-774 not give me the right result - it is probably not a function of bad reaction chemicals - it is more plausible that it is a function of the meter - with other words - a technical problem. My first Red Sea pro test show a result rather similar to my Triton result 2 weeks ago. The last 4 Triton tests - my Hanna test meters have shown a result 0.08 ppm above Triton result with one exception there the Hanna show figures far away from Triton result. One of the > 0.08 tests was done with my old Hi-713 - and was the reason why I bought a new one.

I will do a couple of test the following days and see whats happen but the right answer I will not get before I can test both against a Triton analyse. I do Triton around every three months.

But - it is important to stress that this is valid for my meter - it does not mean that it is valid for all Hanna´s out there. In my case - I trust the results from Triton but if I only had test between Red Sea Pro and Hi-774 - I probably had state that the Red Sea Pro can´t be trusted. In my case - I have - before my test with Red Sea Pro - two indications that I had to trust Triton over my Hi-774. Knowledge about the Triton Method of ICP testing and my IRL observations of my aquarium. Maybe - the Red Sea Pro PO4 test will give me a third indication of not trust MY Hi-774. If I can show that the difference between Red Sea Pro and my Hi-774 is stable and the Red Sea Pro is showing close to Triton - it does not matter what I read on my Hi-774 - it is only a subtraction to do in order to get a valid result. But my test serie of more than 10 readings with the same zero and the same sample show that the result many time are plus/minus 0.02 around a average value. it is in order with Hannas own figures of accuracy. A second test this morning show concentration between 0.08 and 0.12 with Red Sea Pro and a an average of 0,18 with mine Hi-774. See attached excel file.

The photos have been taken with my Olympus TG-6, microscope - gaffling and with adjusted white balance. In next session (I will update the excel file) I will take with photos of all concentrations including zero.

Sincerely Lasse

Thank you for your detailed reply @Lasse !

 

[AstroMelly]

Wow - what a great thread and totally relevant to my current situation. Worthy of a mini reboot imo.

I too have the Hanna 736 ULR Phosphorous checker and am seeing much higher readings compared to my latest ICP. I have done two other ICPs - both taken at the same time/date in mid September - one with Triton and another with ATI - with the ATI you get an RO water analysis as well. I'm attaching them all here.

I purchased the Hanna checker in late November 2022 and at first was not aware of the x3.006 modifier that had to be applied. The readings I was seeing seemed to be roughly ballpark with our other tests (prior to applying the multiplier!). Only in the last month or so I discovered that we were way higher in the Hanna than our other tests. I went back and adjusted all the previous values accordingly. You can (hopefully) see all my parameters here - https://www.aquaticlog.com/aquariums/astromelly/1

Prior to using the Hanna we were using the RedSea PO4 test (I also have the Nyos PO4 test kit). First test with the Hanna was November 26th (0.091 ppm P = 0.279 ppm PO4)!

Right now our tank has high nitrates (about 30) - check the aquatic log link above for the history. Since November 19th 2022 we have been running RowaPhos in a reactor and this has been lowering the P(O4) readings in the Hanna but this has still not got down to where I would have liked - I'm doing my best not to chase the numbers but would like to see <0.04 ppm PO4 or similar. I would like Nitrates <10 ideally which is where we were for a long time previously. I'm using Salifert NO3 test kit for Nitrates. I started dosing RedSea NO/POX at half the recommended dose 10 days ago.

Our latest Triton ICP was taken and posted on 1st Jan 2023 but got delayed - the results were not shared with me until Jan 26th last week - I'm assuming this was when the sample was tested - the P reading was 6 ppb = 0.0168 ppm PO4 and that is where my search for an explanation began. The Hanna showed 0.032 ppm P = 0.098 ppm PO4 a day later.

The latest PO4 test - I ran all the home tests I have:
Nyos - < 0.025ppm
Red Sea ~0.03ppm
Hanna P in ppb - 29, 17, 21, 23 - first one was same tube for C1 and C2. Last 3 were using different C1 tube.
I am discarding the Hanna results for now as Triton ICP sample taken 1st Jan analysed on 26th Jan gives 0.0168 ppm PO4.
29 = 0.089 ppm PO4
17 = 0.052
21 = 0.064 (*) I would say this would be the Reading to take but it is still too high compared to others
23 = 0.070

So it seems to me this thread is extremely relevant and I (as I assume others who have contributed) asked Triton for any possible explanation - Julian from Triton kindly pointed me to the thread which is linked to in this thread which explains how they could read higher than my home test but this is not the case.

In conclusion, the only way I can think that this may be happening for what seems like quite a few folks, would be that somehow the phosphorous contained in the sample is settling, combining or otherwise being incorporated within some semi-solid matter (bacterial film perhaps) inside the sample vessel over time. This would assume that once Triton accept the sample they perform some pre-testing operation that would filter or otherwise separate the solid matter (centrifuge?) from the tube, and with it - supposedly - some of the phosphorous previously contained in the water. I did see this mentioned earlier in the thread as a possible explanation although the details of this process elude me.

Great thread and kudos to you @Rick Mathew (and others) for the hard work trying to get to the bottom of the matter.

Thanks!

 

[Rick Mathew]

Wow - what a great thread and totally relevant to my current situation. Worthy of a mini reboot imo.

I too have the Hanna 736 ULR Phosphorous checker and am seeing much higher readings compared to my latest ICP. I have done two other ICPs - both taken at the same time/date in mid September - one with Triton and another with ATI - with the ATI you get an RO water analysis as well. I'm attaching them all here.

I purchased the Hanna checker in late November 2022 and at first was not aware of the x3.006 modifier that had to be applied. The readings I was seeing seemed to be roughly ballpark with our other tests (prior to applying the multiplier!). Only in the last month or so I discovered that we were way higher in the Hanna than our other tests. I went back and adjusted all the previous values accordingly. You can (hopefully) see all my parameters here - https://www.aquaticlog.com/aquariums/astromelly/1

Prior to using the Hanna we were using the RedSea PO4 test (I also have the Nyos PO4 test kit). First test with the Hanna was November 26th (0.091 ppm P = 0.279 ppm PO4)!

Right now our tank has high nitrates (about 30) - check the aquatic log link above for the history. Since November 19th 2022 we have been running RowaPhos in a reactor and this has been lowering the P(O4) readings in the Hanna but this has still not got down to where I would have liked - I'm doing my best not to chase the numbers but would like to see <0.04 ppm PO4 or similar. I would like Nitrates <10 ideally which is where we were for a long time previously. I'm using Salifert NO3 test kit for Nitrates. I started dosing RedSea NO/POX at half the recommended dose 10 days ago.

Our latest Triton ICP was taken and posted on 1st Jan 2023 but got delayed - the results were not shared with me until Jan 26th last week - I'm assuming this was when the sample was tested - the P reading was 6 ppb = 0.0168 ppm PO4 and that is where my search for an explanation began. The Hanna showed 0.032 ppm P = 0.098 ppm PO4 a day later.

The latest PO4 test - I ran all the home tests I have:
Nyos - < 0.025ppm
Red Sea ~0.03ppm
Hanna P in ppb - 29, 17, 21, 23 - first one was same tube for C1 and C2. Last 3 were using different C1 tube.
I am discarding the Hanna results for now as Triton ICP sample taken 1st Jan analysed on 26th Jan gives 0.0168 ppm PO4.
29 = 0.089 ppm PO4
17 = 0.052
21 = 0.064 (*) I would say this would be the Reading to take but it is still too high compared to others
23 = 0.070

So it seems to me this thread is extremely relevant and I (as I assume others who have contributed) asked Triton for any possible explanation - Julian from Triton kindly pointed me to the thread which is linked to in this thread which explains how they could read higher than my home test but this is not the case.

In conclusion, the only way I can think that this may be happening for what seems like quite a few folks, would be that somehow the phosphorous contained in the sample is settling, combining or otherwise being incorporated within some semi-solid matter (bacterial film perhaps) inside the sample vessel over time. This would assume that once Triton accept the sample they perform some pre-testing operation that would filter or otherwise separate the solid matter (centrifuge?) from the tube, and with it - supposedly - some of the phosphorous previously contained in the water. I did see this mentioned earlier in the thread as a possible explanation although the details of this process elude me.

Great thread and kudos to you @Rick Mathew (and others) for the hard work trying to get to the bottom of the matter.

Thanks!

Thank you for your kindness...Here is another thread that you might find useful with regards to ICP results https://www.reef2reef.com/ams/how-we-use-icp-oes-results-of-unknown-accuracy-and-precision.862/

This "storage" or "transport" time and its effect on our measurement is not just confined to ICP results. It also pertains to our at home testing. Because we are measuring very small amounts (ppb, ppm) in a biologically active system we need to pay attention to the handling of our water samples...this is a science unto itself....Thanks again!