Are Hanna Checkers The Gold Standard In Hobby Grade Test Kits?

[nereefpat]

I’ve noticed how Reefers often compare various test kits to Hanna checkers, and wonder if they are considered the gold standard in hobby grade testers? And if they are, why buy anything else? I get having backups, but it seems some people really have a hard time figuring out what to believe, and tend to go with what the Hanna checker says anyway. What’s your take on it?

Which parameter?

 

[VintageReefer]

I am a big user of Hanna Checkers. I along with @taricha and @Rick Mathew have pressure tested these devices. They generally do what they are suppose to do consistently. The point is that they have their limits. If we wanted to improve on accuracy, we would probably use a spectrophotometer to measure color intensity. I rarely do because the questions I need answering are more like “yes-no” questions rather than trying to tell the difference in concentration of 0.01 v 0.02 ppm.

I think this thread has gotten out of hand. We all need to forget the term gold standard of testing. Obviously spectrometers and labs are “gold standard” and more accurate than hobby grade tests

I think what’s being asked is basically, if a new reefer, or experienced reefer, needed to go out and buy test kits, what is considered the best for consistent and reliable results.

And I feel these digital testers take all the guess work out of the results, there’s no colors to interpret, a color doesn’t end up in between two colors on a reference chart, room lighting doesn’t matter.

Compared to the other brands, the result is put on a screen and there is no interpretation, and once you get familiar with the steps, they are easy to use the same way each week and have consistent results

 

[Reefer Matt]

We all need to forget the term gold standard of testing. Obviously spectrometers and labs are “gold standard” and more accurate than hobby grade tests

Yeah, to me the term “Gold Standard” in this case just means the one you believe the most, out of the hobby grade kits. It’s all a matter of opinion.

 

[GARRIGA]

Measurement of coral growth wouldn’t be very useful if we could not put it into context, say its maximum growth rate. If I want to know whether the conditions I am supplying the coral are any good, growth rate is a handy metric. Answering the question whether the nitrate, phosphate or trace elements are at a good level could be answered by checking the coral growth rate. Of course, it would be tricky if all of these parameters were fluctuating all over the place.

Appreciate that yet we're just hobbyist that think we are chemist or biologist yet most likely clueless how to perform these tests. End of day, how many experienced reefers have struggled to keep most corals outside these self induced ranges? Based anecdotally on what I've read. Seems to be the majority although bragging about 50 ppm nitrates likely frowned upon and therefore rarely mentioned yet mentioned it has. PO4 at 0.03-0.09 rather tight rope to walk and still few corals require it yet industry promotes is as if that's gold standard to success. If it turns out it is. I'll be happy growing corals with warts and photosynthetic sponges

 

[VintageReefer]

Yeah, to me the term “Gold Standard” in this case just means the one you believe the most, out of the hobby grade kits. It’s all a matter of opinion.

This has happened to me in other threads. Where I say something broad or general and it’s taken literally. And then everything becomes derailed. Sometimes one extra word or sentence as a preface is needed in the first post. Because many people read the first post then jump to the end and miss the clarification in the middle

 

[Reefer Matt]

This has happened to me in other threads. Where I say something broad or general and it’s taken literally. And then everything becomes derailed. Sometimes one extra word or sentence as a preface is needed in the first post. Because many people read the first post then jump to the end and miss the clarification in the middle

Yeah, that’s why I tend to stay out of the chemistry forum. I try to keep my posts simple, but they can get misunderstood quickly if the right words aren’t used, and confuse people. My posts are usually like a Devil’s Advocate to get Reefers thinking and talking. But sometimes something cool comes up that we all benefit from.

 

[areefer01]

And I feel these digital testers take all the guess work out of the results, there’s no colors to interpret, a color doesn’t end up in between two colors on a reference chart, room lighting doesn’t matter.

Yes, and no. The hobbyist still has to be consistent in getting all of the reagent out of the packet. Or they have to fill up the test vial with the correct amount. Or if the kit uses a battery what is its charge and does that play a role in the measurement. Shaken or stirred? Vigorously? 2 minutes, 3 minutes? Reagents expired? Lot number good or bad?

Human factor still plays a role. Probably why Bob over in PMEL has a job description that caters to these types of things.

 

[Reefer Matt]

Yes, and no. The hobbyist still has to be consistent in getting all of the reagent out of the packet. Or they have to fill up the test vial with the correct amount. Or if the kit uses a battery what is its charge and does that play a role in the measurement. Shaken or stirred? Vigorously? 2 minutes, 3 minutes? Reagents expired? Lot number good or bad?

Human factor still plays a role. Probably why Bob over in PMEL has a job description that caters to these types of things.

I wonder how much of that actually matters though? Do you really need a fully charged battery and every granule of reagent? If I shake the vial for 1:45 minutes instead of 2:00, does it really matter? Or are we assuming it does?

 

[FUNGI]

For manual test I only use Hanna Checkers and have tested them against Fauna Marin MRS and they come back dead on every time. I also use the salinity checker and back it up with refrac and have never had a problem.

I have two KH Guardian and a Trident that does automatic testing and the results come back with in range. I think Hanna is the “Gold Standard”!

Bro,....you got to do this in excel........you can visualize trends in a second.....

 

[VintageReefer]

I wonder how much of that actually matters though? Do you really need a fully charged battery and every granule of reagent? If I shake the vial for 1:45 minutes instead of 2:00, does it really matter? Or are we assuming it does?

The device will tell you when battery is insufficient for testing. And they last a long time

Do your best to get all the reagent out. Should be easy to be consistent each time. I cut two sides. Fold to make a V shape. And tap it all out

Shake, invert, whatever according to directions. Do the same thing each time. That way there’s no variation.

Easy to be consistent if someone is consistent in their methods

 

[MnFish1]

I am a big user of Hanna Checkers. I along with @taricha and @Rick Mathew have pressure tested these devices. They generally do what they are suppose to do consistently. The point is that they have their limits. If we wanted to improve on accuracy, we would probably use a spectrophotometer to measure color intensity. I rarely do because the questions I need answering are more like “yes-no” questions rather than trying to tell the difference in concentration of 0.01 v 0.02 ppm.

The problem (unless you did?) if you didn't 'pressure test' the rest of the tests being discussed - doesn't mean much or am I misunderstanding (agree they have their limits)

 

[Randy Holmes-Farley]

I think this thread has gotten out of hand. We all need to forget the term gold standard of testing. Obviously spectrometers and labs are “gold standard” and more accurate than hobby grade tests

I think what’s being asked is basically, if a new reefer, or experienced reefer, needed to go out and buy test kits, what is considered the best for consistent and reliable results.

And I feel these digital testers take all the guess work out of the results, there’s no colors to interpret, a color doesn’t end up in between two colors on a reference chart, room lighting doesn’t matter.

Compared to the other brands, the result is put on a screen and there is no interpretation, and once you get familiar with the steps, they are easy to use the same way each week and have consistent results

Well, if you are asking what is the best test for a new reefer to get, that’s a very different question than whether it is the best test for an experienced reefer.

Without question, the Hanna conductivity meter and the Hanna pH meter are far from the best devices used by ordinary reefers for these parameters.

 

[VintageReefer]

Well, if you are asking what is the best test for a new reefer to get, that’s a very different question than whether it is the best test for an experienced reefer.

Without question, the Hanna conductivity meter and the Hanna pH meter are far from the best devices used by ordinary reefers for these parameters.

I would agree. Those are trash

 

[taricha]

There are two advantages that hanna has over most hobby test kits.
1) digital eyeball allows quantification that human eyeballs+color cards are really bad at.
2) single-use packets allows reagents to be opened for the first time at the moment of the actual test. This avoids degradation issues that other kits have to contend with if the reagents get opened over and over and exposed to oxygen and humidity. Some hobby kits lose performance over time for these reasons.

I like hanna for many things. That said, if it can be measured by titration, I personally prefer the titration over the hanna test: Alk, Ca, Mg. Titrations are quantified by titrant volume and the eyeball color becomes mostly a non-issue.
Salinity and pH - I also prefer stuff other than Hanna.

 

[Rick Mathew]

Interesting discussion,

I am a big Hanna Checker user. That being said I would never declarer them “A Gold Standard” , for the same reason Randy stated. A “gold standard” is that which every other measurement is evaluated against with regard to accuracy without any other condition….That is for me defiantly not a Hanna Checker! …..On the other hand

I would say :

• They have Fit for Use* precision
• Depending on the Checker they have a Fit for Use* accuracy
• They are easy to use

I use them because:

• As @taricha said, they provide a digital value that provides a way to statistically evaluate the quality of the measurement. (including accuracy vs. an known standard)
• Eliminate the need to visually assess color changes.
• They are basically simple to use
• The test reagents are lot tested and supplied with certificates of analysis which is also helpful in quality analysis.
• As @taricha also mentions most of the reagents are sealed and opened only at the time of testing preventing reagent degradation due to exposure.

All of that being said, I would like to focus my response on the issue that several others in this thread touched on. Any test is much more than the measurement device or equipment. It is every aspect of the measurement protocol…From taking the sample to recording the final results. This would include but not limited to …The operator, the materials used, the methods employed, the environment…and so on.

I have been involved in testing of materials for over 50 years; ICP, Gas Chromatography, Thermal Testing, UV-Near IR, color difference measurement and many others. In my experience most testing variability was not due to equipment error but systematic errors found in all the other aspects of the testing protocol. This does not mean that equipment is not a source of error, but it is generally not the primary source.

Considering this, in order to evaluate any test method one has to know the error introduced by each of the individual steps in the protocol in order to sort out what the instrument or equipment error is. Without this, any variation seen in the test results can’t be attributed to any individual step on the protocol or the instrument…It’s like blaming a bad meal on the pots and pans without knowing anything about the cook or the ingredients.

Getting back to the original question “Are Hanna Checkers The Gold Standard In Hobby Grade Test Kits?” As @Dan_P said, I have “pressure tested” my Hanna Checkers (listed below). What does that mean? I spent the time to minimize the variability of each of the steps in the individual test protocols (liquid volume measurement, clean glassware….ETC). I then created known standards, some from NIST traceable ICP Standards. I then did multiple (5-10) measurements at each of the known standard levels using the test protocol. Using the data I calculated a Relative Accuracy, Precision and error. I did this same procedure for a small number of other chemical test kits (Salifert Mg, Red Sea Ca and Salifert Sr)

CONCLUSION:

• All of the Hanna Checkers I use have Fit for Use precision and accuracy. They all performed for the most part better than or equal to their Specifications stated accuracy. So If the test is preformed using good laboratory practices (1 )
• The other chemical tests
• Salifert Mg Test (Titration)---Fit for use* precision and accuracy
• Red Sea Ca Test (Titration) ---Fit for use* precision and accuracy
• Salifert Sr Test (Titration) ---Too much variability for my use

Here is an example I posted in 2020 for the HI-758 Calcium Checker

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/post-8120963

Gold Standard??? Don’t think I would say that for I do not have the data to support it, but they are very useful tools and are good for my Fitness for Use.*

* Fitness for use describes the extent to which you can be confident in the measurement results as it relates to the requirements of the individual parameter you are testing. This is sometimes referred to as the “Gage Error” So for example if your requirement for Calcium level is you want to be within 10ppm and your “Gage Error” is 20ppm then the measurement is not Fit For Use…You can read more about this in this article under the section “Vender Evaluation-Gage Variation”

https://www.reef2reef.com/ams/how-we-use-icp-oes-results-of-unknown-accuracy-and-precision.862/

Hanna Checkers I Use
HI-772 ALK......HI-764 (ADAPTED FOR NO3 TEST)....HI-705 Si (LR)
HI-758 Ca........HI- 736 P.............................................HI- 746 Fe (LR)
HI-783 Mg.......HI-747 Cu (LR)................................... HI-707 (ADAPTED FOR IODINE TEST)
HI-713 (ADAPTED FOR POTASSIUM TEST)...............HI-96702 Cu (HR)


(1)
If you are interested in learning more about water testing in general and good laboratory practices, go here https://www.reef2reef.com/ams/authors/rick-mathew.66447/ and read the articles titled “GETTING IT RIGHT” Part 1-4.

All the best

Rick

 

[areefer01]

Interesting discussion,

I am a big Hanna Checker user. That being said I would never declarer them “A Gold Standard” , for the same reason Randy stated. A “gold standard” is that which every other measurement is evaluated against with regard to accuracy without any other condition….That is for me defiantly not a Hanna Checker! …..On the other hand

I would say :

• They have Fit for Use* precision
• Depending on the Checker they have a Fit for Use* accuracy
• They are easy to use

I use them because:

• As @taricha said, they provide a digital value that provides a way to statistically evaluate the quality of the measurement. (including accuracy vs. an known standard)
• Eliminate the need to visually assess color changes.
• They are basically simple to use
• The test reagents are lot tested and supplied with certificates of analysis which is also helpful in quality analysis.
• As @taricha also mentions most of the reagents are sealed and opened only at the time of testing preventing reagent degradation due to exposure.

All of that being said, I would like to focus my response on the issue that several others in this thread touched on. Any test is much more than the measurement device or equipment. It is every aspect of the measurement protocol…From taking the sample to recording the final results. This would include but not limited to …The operator, the materials used, the methods employed, the environment…and so on.

I have been involved in testing of materials for over 50 years; ICP, Gas Chromatography, Thermal Testing, UV-Near IR, color difference measurement and many others. In my experience most testing variability was not due to equipment error but systematic errors found in all the other aspects of the testing protocol. This does not mean that equipment is not a source of error, but it is generally not the primary source.

Considering this, in order to evaluate any test method one has to know the error introduced by each of the individual steps in the protocol in order to sort out what the instrument or equipment error is. Without this, any variation seen in the test results can’t be attributed to any individual step on the protocol or the instrument…It’s like blaming a bad meal on the pots and pans without knowing anything about the cook or the ingredients.

Getting back to the original question “Are Hanna Checkers The Gold Standard In Hobby Grade Test Kits?” As @Dan_P said, I have “pressure tested” my Hanna Checkers (listed below). What does that mean? I spent the time to minimize the variability of each of the steps in the individual test protocols (liquid volume measurement, clean glassware….ETC). I then created known standards, some from NIST traceable ICP Standards. I then did multiple (5-10) measurements at each of the known standard levels using the test protocol. Using the data I calculated a Relative Accuracy, Precision and error. I did this same procedure for a small number of other chemical test kits (Salifert Mg, Red Sea Ca and Salifert Sr)

CONCLUSION:

• All of the Hanna Checkers I use have Fit for Use precision and accuracy. They all performed for the most part better than or equal to their Specifications stated accuracy. So If the test is preformed using good laboratory practices (1 )
• The other chemical tests
• Salifert Mg Test (Titration)---Fit for use* precision and accuracy
• Red Sea Ca Test (Titration) ---Fit for use* precision and accuracy
• Salifert Sr Test (Titration) ---Too much variability for my use

Here is an example I posted in 2020 for the HI-758 Calcium Checker

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/post-8120963

Gold Standard??? Don’t think I would say that for I do not have the data to support it, but they are very useful tools and are good for my Fitness for Use.*

* Fitness for use describes the extent to which you can be confident in the measurement results as it relates to the requirements of the individual parameter you are testing. This is sometimes referred to as the “Gage Error” So for example if your requirement for Calcium level is you want to be within 10ppm and your “Gage Error” is 20ppm then the measurement is not Fit For Use…You can read more about this in this article under the section “Vender Evaluation-Gage Variation”

https://www.reef2reef.com/ams/how-we-use-icp-oes-results-of-unknown-accuracy-and-precision.862/

Hanna Checkers I Use
HI-772 ALK HI-764 (ADAPTED FOR NO3 TEST) HI-705 Si (LR)
HI-758 Ca HI- 736 P HI- 746 Fe (LR)
HI-783 Mg HI-747 Cu (LR) HI-707 (ADAPTED FOR IODINE TEST)
HI-713 (ADAPTED FOR POTASSIUM TEST) HI-96702 Cu (HR)


(1)
If you are interested in learning more about water testing in general and good laboratory practices, go here https://www.reef2reef.com/ams/authors/rick-mathew.66447/ and read the articles titled “GETTING IT RIGHT” Part 1-4.

All the best

Rick

Did you mean to have everything in bold?

 

[Rick Mathew]

Did you mean to have everything in bold?

I did...easier to read for some...Thanks for checking in

 

[Reefer Matt]

Interesting discussion,

I am a big Hanna Checker user. That being said I would never declarer them “A Gold Standard” , for the same reason Randy stated. A “gold standard” is that which every other measurement is evaluated against with regard to accuracy without any other condition….That is for me defiantly not a Hanna Checker! …..On the other hand

I would say :

• They have Fit for Use* precision
• Depending on the Checker they have a Fit for Use* accuracy
• They are easy to use

I use them because:

• As @taricha said, they provide a digital value that provides a way to statistically evaluate the quality of the measurement. (including accuracy vs. an known standard)
• Eliminate the need to visually assess color changes.
• They are basically simple to use
• The test reagents are lot tested and supplied with certificates of analysis which is also helpful in quality analysis.
• As @taricha also mentions most of the reagents are sealed and opened only at the time of testing preventing reagent degradation due to exposure.

All of that being said, I would like to focus my response on the issue that several others in this thread touched on. Any test is much more than the measurement device or equipment. It is every aspect of the measurement protocol…From taking the sample to recording the final results. This would include but not limited to …The operator, the materials used, the methods employed, the environment…and so on.

I have been involved in testing of materials for over 50 years; ICP, Gas Chromatography, Thermal Testing, UV-Near IR, color difference measurement and many others. In my experience most testing variability was not due to equipment error but systematic errors found in all the other aspects of the testing protocol. This does not mean that equipment is not a source of error, but it is generally not the primary source.

Considering this, in order to evaluate any test method one has to know the error introduced by each of the individual steps in the protocol in order to sort out what the instrument or equipment error is. Without this, any variation seen in the test results can’t be attributed to any individual step on the protocol or the instrument…It’s like blaming a bad meal on the pots and pans without knowing anything about the cook or the ingredients.

Getting back to the original question “Are Hanna Checkers The Gold Standard In Hobby Grade Test Kits?” As @Dan_P said, I have “pressure tested” my Hanna Checkers (listed below). What does that mean? I spent the time to minimize the variability of each of the steps in the individual test protocols (liquid volume measurement, clean glassware….ETC). I then created known standards, some from NIST traceable ICP Standards. I then did multiple (5-10) measurements at each of the known standard levels using the test protocol. Using the data I calculated a Relative Accuracy, Precision and error. I did this same procedure for a small number of other chemical test kits (Salifert Mg, Red Sea Ca and Salifert Sr)

CONCLUSION:

• All of the Hanna Checkers I use have Fit for Use precision and accuracy. They all performed for the most part better than or equal to their Specifications stated accuracy. So If the test is preformed using good laboratory practices (1 )
• The other chemical tests
• Salifert Mg Test (Titration)---Fit for use* precision and accuracy
• Red Sea Ca Test (Titration) ---Fit for use* precision and accuracy
• Salifert Sr Test (Titration) ---Too much variability for my use

Here is an example I posted in 2020 for the HI-758 Calcium Checker

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/post-8120963

Gold Standard??? Don’t think I would say that for I do not have the data to support it, but they are very useful tools and are good for my Fitness for Use.*

* Fitness for use describes the extent to which you can be confident in the measurement results as it relates to the requirements of the individual parameter you are testing. This is sometimes referred to as the “Gage Error” So for example if your requirement for Calcium level is you want to be within 10ppm and your “Gage Error” is 20ppm then the measurement is not Fit For Use…You can read more about this in this article under the section “Vender Evaluation-Gage Variation”

https://www.reef2reef.com/ams/how-we-use-icp-oes-results-of-unknown-accuracy-and-precision.862/

Hanna Checkers I Use
HI-772 ALK......HI-764 (ADAPTED FOR NO3 TEST)....HI-705 Si (LR)
HI-758 Ca........HI- 736 P.............................................HI- 746 Fe (LR)
HI-783 Mg.......HI-747 Cu (LR)................................... HI-707 (ADAPTED FOR IODINE TEST)
HI-713 (ADAPTED FOR POTASSIUM TEST)...............HI-96702 Cu (HR)


(1)
If you are interested in learning more about water testing in general and good laboratory practices, go here https://www.reef2reef.com/ams/authors/rick-mathew.66447/ and read the articles titled “GETTING IT RIGHT” Part 1-4.

All the best

Rick

Thank you for your very detailed response! This thread was started because I noticed Reefers consistently saying that their (other brand) test kit is off because the Hanna Checker reads differently. Have you, @taricha, or @Dan_P done an experiment to test how much you can vary the shake time, reagent amount, or water sample amount of Hanna Checkers and still get readings consistent with their margin of error? (In other words, mess it up on purpose.) There are some that believe that every reagent granule, ml, and second are critical for accurate testing with them.

 

[Dan_P]

Interesting discussion,

I am a big Hanna Checker user. That being said I would never declarer them “A Gold Standard” , for the same reason Randy stated. A “gold standard” is that which every other measurement is evaluated against with regard to accuracy without any other condition….That is for me defiantly not a Hanna Checker! …..On the other hand

I would say :

• They have Fit for Use* precision
• Depending on the Checker they have a Fit for Use* accuracy
• They are easy to use

I use them because:

• As @taricha said, they provide a digital value that provides a way to statistically evaluate the quality of the measurement. (including accuracy vs. an known standard)
• Eliminate the need to visually assess color changes.
• They are basically simple to use
• The test reagents are lot tested and supplied with certificates of analysis which is also helpful in quality analysis.
• As @taricha also mentions most of the reagents are sealed and opened only at the time of testing preventing reagent degradation due to exposure.

All of that being said, I would like to focus my response on the issue that several others in this thread touched on. Any test is much more than the measurement device or equipment. It is every aspect of the measurement protocol…From taking the sample to recording the final results. This would include but not limited to …The operator, the materials used, the methods employed, the environment…and so on.

I have been involved in testing of materials for over 50 years; ICP, Gas Chromatography, Thermal Testing, UV-Near IR, color difference measurement and many others. In my experience most testing variability was not due to equipment error but systematic errors found in all the other aspects of the testing protocol. This does not mean that equipment is not a source of error, but it is generally not the primary source.

Considering this, in order to evaluate any test method one has to know the error introduced by each of the individual steps in the protocol in order to sort out what the instrument or equipment error is. Without this, any variation seen in the test results can’t be attributed to any individual step on the protocol or the instrument…It’s like blaming a bad meal on the pots and pans without knowing anything about the cook or the ingredients.

Getting back to the original question “Are Hanna Checkers The Gold Standard In Hobby Grade Test Kits?” As @Dan_P said, I have “pressure tested” my Hanna Checkers (listed below). What does that mean? I spent the time to minimize the variability of each of the steps in the individual test protocols (liquid volume measurement, clean glassware….ETC). I then created known standards, some from NIST traceable ICP Standards. I then did multiple (5-10) measurements at each of the known standard levels using the test protocol. Using the data I calculated a Relative Accuracy, Precision and error. I did this same procedure for a small number of other chemical test kits (Salifert Mg, Red Sea Ca and Salifert Sr)

CONCLUSION:

• All of the Hanna Checkers I use have Fit for Use precision and accuracy. They all performed for the most part better than or equal to their Specifications stated accuracy. So If the test is preformed using good laboratory practices (1 )
• The other chemical tests
• Salifert Mg Test (Titration)---Fit for use* precision and accuracy
• Red Sea Ca Test (Titration) ---Fit for use* precision and accuracy
• Salifert Sr Test (Titration) ---Too much variability for my use

Here is an example I posted in 2020 for the HI-758 Calcium Checker

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/post-8120963

Gold Standard??? Don’t think I would say that for I do not have the data to support it, but they are very useful tools and are good for my Fitness for Use.*

* Fitness for use describes the extent to which you can be confident in the measurement results as it relates to the requirements of the individual parameter you are testing. This is sometimes referred to as the “Gage Error” So for example if your requirement for Calcium level is you want to be within 10ppm and your “Gage Error” is 20ppm then the measurement is not Fit For Use…You can read more about this in this article under the section “Vender Evaluation-Gage Variation”

https://www.reef2reef.com/ams/how-we-use-icp-oes-results-of-unknown-accuracy-and-precision.862/

Hanna Checkers I Use
HI-772 ALK......HI-764 (ADAPTED FOR NO3 TEST)....HI-705 Si (LR)
HI-758 Ca........HI- 736 P.............................................HI- 746 Fe (LR)
HI-783 Mg.......HI-747 Cu (LR)................................... HI-707 (ADAPTED FOR IODINE TEST)
HI-713 (ADAPTED FOR POTASSIUM TEST)...............HI-96702 Cu (HR)


(1)
If you are interested in learning more about water testing in general and good laboratory practices, go here https://www.reef2reef.com/ams/authors/rick-mathew.66447/ and read the articles titled “GETTING IT RIGHT” Part 1-4.

All the best

Rick

Thanks Rick. Just what the discussion needed.
.

 

[Dan_P]

Thank you for your very detailed response! This thread was started because I noticed Reefers consistently saying that their (other brand) test kit is off because the Hanna Checker reads differently. Have you, @taricha, or @Dan_P done an experiment to test how much you can vary the shake time, reagent amount, or water sample amount of Hanna Checkers and still get readings consistent with their margin of error? (In other words, mess it up on purpose.) There are some that believe that every reagent granule, ml, and second are critical for accurate testing with them.

The closet I came to any stress testing was purposely using less reagent for the phosphate test. If I recall, you won’t see a statistical difference until you use less than 90% of the chemical in the packet. This was done with only one concentration of PO4. I imagine at higher PO4 concentrations, the test might not be so forgiving.