hanna alk checker post your results

[Art2249]

This is an experiment with the hanna alk checker. i recently replied to a thread with my method for using this test. Someone asked me why i did the test that way, since it was not according to the manufacturer instructions. i replied that it worked well that way for me and my coral seemed happy. I am curious if anyone else does the test this way.
the main difference is that i don't use the syringe extension when i draw out the reagent. i have always done the test this way because i reasoned at the start that using the extension would only waste reagent.
i have read many posts here that hanna checkers are not so accurate. the way i do the test, results are always accurate within .1. i have checked this result many times against salifert and always it comes within .1.
i am interested to see if other people have tried this and if their results are similar. it would also be interesting to see those results against tests other than salifert.
let me state that the salifert results are measured when the color change BEGINS. i read a post once that this was the time to take the measure. also, i always store the hanna vial with rodi water. always wipe it with a lint free cloth. and always turn the vial in the same direction.

 

[P-Dub]

I reviewed your started threads and could not find the discussion regarding your testing methods. Would you care to share your methods here again?

 

[dferran1]

I think that the inaccuracy with the Hannas is from improper use. Many do not realize that fingerprints or smudges, even dust or particles from a household cloth, on the cuvette will lead to erroneous results. In a laboratory environment, when dealing with a spectrophotometer, one would be wearing nitrile gloves to handle the cuvette, and will be wiping the cuvette with a kimWipe before taking any measurements or zeroing the instrument. I have thus found the Hannas to be more trouble than they are worth. I stick with salifert which has a 20+ year reputation of being one of the best and most accurate test kits on the market.

As far as the color changing, you have to accept some inherent error when testing in this manner. It is called titration error. When the indicator reagent used in the test kit actually produces the visible color change, it will not correspond exactly to the stoichiometric amount of titrant required to react completely with the analyte. In other words, you are detecting the endpoint with the color change in the test kit, which in simple terms, is a slight "overshoot." This will not correspond to the equivalence point ( the actual amount of reagent needed, that will not in reality align with the color change.) With this said, I would run the titration to the end point ( to the color change) and just accept there will be a small amount of error. For hobby purposes, I think this is fine. Keep in your mind then, if you measure a certain alkalinity with salifert, for example, your actually alkalinity may be a few tenths of a dKH unit lower, due to the titration error and the extra reagent you needed to "overshoot", to produce the color change for you to visually observe.

You are not wasting any reagent with the syringe extension. It is the same concept as in the salifert test kit, in which there will be a small space of air in the syringe below the piston, which corresponds to the titrant taken up into the tip of the syringe. With this said, I does not matter if you are using the syringe extension or not, if you are delivering 1 mL of the reagent to the cuvette. I would, however, use the syringe extension and follow the directions exactly for the sake of consistency and reproducibility.

 

[Art2249]

https://www.reef2reef.com/threads/alkalinity-standard.538308/page-2#post-5576836 I didn't start the thread but here it is. I'm still interested in seeing if anyone else has tried doing the test without the syringe extension and posting their results.

 

[Art2249]

I think that the inaccuracy with the Hannas is from improper use. Many do not realize that fingerprints or smudges, even dust or particles from a household cloth, on the cuvette will lead to erroneous results. In a laboratory environment, when dealing with a spectrophotometer, one would be wearing nitrile gloves to handle the cuvette, and will be wiping the cuvette with a kimWipe before taking any measurements or zeroing the instrument. I have thus found the Hannas to be more trouble than they are worth. I stick with salifert which has a 20+ year reputation of being one of the best and most accurate test kits on the market.

As far as the color changing, you have to accept some inherent error when testing in this manner. It is called titration error. When the indicator reagent used in the test kit actually produces the visible color change, it will not correspond exactly to the stoichiometric amount of titrant required to react completely with the analyte. In other words, you are detecting the endpoint with the color change in the test kit, which in simple terms, is a slight "overshoot." This will not correspond to the equivalence point ( the actual amount of reagent needed, that will not in reality align with the color change.) With this said, I would run the titration to the end point ( to the color change) and just accept there will be a small amount of error. For hobby purposes, I think this is fine. Keep in your mind then, if you measure a certain alkalinity with salifert, for example, your actually alkalinity may be a few tenths of a dKH unit lower, due to the titration error and the extra reagent you needed to "overshoot", to produce the color change for you to visually observe.

You are not wasting any reagent with the syringe extension. It is the same concept as in the salifert test kit, in which there will be a small space of air in the syringe below the piston, which corresponds to the titrant taken up into the tip of the syringe. With this said, I does not matter if you are using the syringe extension or not, if you are delivering 1 mL of the reagent to the cuvette. I would, however, use the syringe extension and follow the directions exactly for the sake of consistency and reproducibility.

As i said before, many people have posted about inaccurate results (within .5). most of us aren't working in a laboratory. i am interested to see if more accurate results can be obtained without the syringe extension. this is what i have observed personally.

 

[Nathan Milender]

I do not use the syringe extension as I just did not see the point of it. I do shake the reagent before opening. I do make sure to rid the syringe of bubbles and sometimes have to re-draw a sample. I do use a cloth and wipe it off before putting it into the checker both times. I do not use nitrile gloves or chem-wipes.

Overall I am happy with it. It is quick. I am ok with a small error as I shoot for a Dk of 10 and quite frankly I doubt .5 either way is going to matter. I also doubt that small error on reagent measuring is going to matter. A long skinny syringe to measure 1 ml diluted in 10 ml (with much more error than the syringe) is likely not going to have a huge effect. I doubt the machine has much error, and I suspect the error it has is clinically insignificant.

 

[Art2249]

let me rephrase the question, for all the wannabe scientists out there. Rather than having a debate, conduct an experiment. Use the hanna checker without the syringe extension. Post your results!!!

 

[Justfebreezeit]

I get repeatable results with no issue.

I use the tip it came with. I'll state my procedure for review.

1. Fill cuvette with tank water and shake to rinse. Dump in sink.
2. Fill cuvette with tank water to 10ml (bottom of meniscus to bottom of the 10ml line)
3. Turn on checker
4. Wipe cuvette with kimtech wipe and insert into checker (at C1) with the 10ml mark facing forward
5. Draw 1ml reagent and fill cuvette. I hold the cuvette either by the cap or with the kimtech wipe after C1 is complete)
6. Invert 5 times and reinsert to cuvette.
7. Reading
8. Rinse cuvette, cap, and syringe in RODI before storage.

Edit: I imagine the syringe extension is just to make it easier to draw the reagent.

 

[Art2249]

I get repeatable results with no issue.

I use the tip it came with. I'll state my procedure for review.

1. Fill cuvette with tank water and shake to rinse. Dump in sink.
2. Fill cuvette with tank water to 10ml (bottom of meniscus to bottom of the 10ml line)
3. Turn on checker
4. Wipe cuvette with kimtech wipe and insert into checker (at C1) with the 10ml mark facing forward
5. Draw 1ml reagent and fill cuvette. I hold the cuvette either by the cap or with the kimtech wipe after C1 is complete)
6. Invert 5 times and reinsert to cuvette.
7. Reading
8. Rinse cuvette, cap, and syringe in RODI before storage.

Edit: I imagine the syringe extension is just to make it easier to draw the reagent.

thats the same way i do it, minus the syringe extension. plus i get consistent results, i'm mostly trying to figure out how accurate it is.

 

[dferran1]

let me rephrase the question, for all the wannabe scientists out there. Rather than having a debate, conduct an experiment. Use the hanna checker without the syringe extension. Post your results!!!

Nobody is trying to have a debate with you. We were just trying to help you. However, what you are suggesting is by no means an "experiment." Using the Hannah checker without a syringe tip extension is not an experiment. And obtaining consistent results using a method without the syringe tip, proves absolutely nothing. After reading the thread you linked to and referenced, it seems that other uses have given very good advice already. One member suggested using an alkalinity reference solution, which is a fantastic idea. But, you "persnally think the checker works better without the extension and is more accurate that way."

Good luck!

Edit: In attempt to be cordial, I'll suggest something closer to an experiment. Obtain the reference solution. Conduct the test twice, once using the syringe tip extension, and again, in exactly the same way, but without using the syringe tip extension. See which method provides an alkalinity reading closest to the reported alkalinity of the reference solution. This will directly prove or disprove your claim that the absence of the syringe tip extension affords more accurate results, using actual evidence.

 

[Art2249]

you are correct. i need a reference solution. However i disagree on one point. Anytime you try something in order to see the results, that automatically qualifies as an experiment.

 

[Art2249]

Nobody is trying to have a debate with you. We were just trying to help you. However, what you are suggesting is by no means an "experiment." Using the Hannah checker without a syringe tip extension is not an experiment. And obtaining consistent results using a method without the syringe tip, proves absolutely nothing. After reading the thread you linked to and referenced, it seems that other uses have given very good advice already. One member suggested using an alkalinity reference solution, which is a fantastic idea. But, you "persnally think the checker works better without the extension and is more accurate that way."

Good luck!

Edit: In attempt to be cordial, I'll suggest something closer to an experiment. Obtain the reference solution. Conduct the test twice, once using the syringe tip extension, and again, in exactly the same way, but without using the syringe tip extension. See which method provides an alkalinity reading closest to the reported alkalinity of the reference solution. This will directly prove or disprove your claim that the absence of the syringe tip extension affords more accurate results, using actual evidence.

Also, you would need to conduct this test multiple times. And achieve the same results multiple times. At this point, all i am attempting to do is gather data.

 

[dferran1]

you are correct. i need a reference solution. However i disagree on one point. Anytime you try something in order to see the results, that automatically qualifies as an experiment.

OK. After re- reading your original post and thinking more about it, I realized you were suggesting we have members post their alkalinity values taken by two methods- by hanna and by salifert, and post both results for comparison purposes. I'll measure my alkalinity daily, for 7 days, using both methods, and then post the results to see how they compare. I apologize if initially, I failed to address your question directly, or responded too strongly.

 

[JimWelsh]

I'm pretty sure that every instance of the words "accurate" and "accuracy" in this thread should be edited to say "precise" or "precision".

 

[JimWelsh]

 

[Art2249]

OK. After re- reading your original post and thinking more about it, I realized you were suggesting we have members post their alkalinity values taken by two methods- by hanna and by salifert, and post both results for comparison purposes. I'll measure my alkalinity daily, for 7 days, using both methods, and then post the results to see how they compare. I apologize if initially, I failed to address your question directly, or responded too strongly.

Cool! I would like to add one point that makes this topic so difficult. My alk levels are consistent so long as my house is closed. once i open my windows and doors i find that i need to add alk and calcium accordingly. usually that amounts to .1 alk and the corresponding amount of calcium. Which in my tank is 11 ml each.

 

[Art2249]

Cool! I would like to add one point that makes this topic so difficult. My alk levels are consistent so long as my house is closed. once i open my windows and doors i find that i need to add alk and calcium accordingly. usually that amounts to .1 alk and the corresponding amount of calcium. Which in my tank is 11 ml each.

daily

 

[JimWelsh]

Cool! I would like to add one point that makes this topic so difficult. My alk levels are consistent so long as my house is closed. once i open my windows and doors i find that i need to add alk and calcium accordingly. usually that amounts to .1 alk and the corresponding amount of calcium. Which in my tank is 11 ml each.

Alk and calcium levels are not affected by ambient CO2 levels. pH is. Your anecdotal observation implies that perhaps the Hanna alk checker is sensitive to pH changes. I own a Hanna checker, but rarely use it. I wonder if others have reported a similar pH-sensitivity?

 

[dferran1]

Ok guys Ill be using a spreadsheet like this. Just did the test. Got a discrepancy of 0.6 dKH.

 

[dferran1]

Alk and calcium levels are not affected by ambient CO2 levels. pH is. Your anecdotal observation implies that perhaps the Hanna alk checker is sensitive to pH changes. I own a Hanna checker, but rarely use it. I wonder if others have reported a similar pH-sensitivity?

True and not true. The thing to remember is the pH and alkalinity are intimately connected. In other words, in a reef tank, a pH change is almost certainly going to correspond to an alkalinity change, and vice versa, even if we are not detecting this due to limitations on testing or the kinetics with which this is happening. pH levels are affected by ambient CO2 levels, via conversion to carbonic acid. This species is a key player in the Carbonate <-> bicarbonate <-> carbonic acid equilibrium in the tank. A Basic chemical principle is that in a state of multiple equilibria, all must be satisfied. In other words, if the ambient CO2 level rises, then the pH drops, and the equilibrium concentrations of one or more of the above must change to compensate.