Hanna Alkalinity Reagent

[Reef man 89]

Hanna Instruments here, thank you for using our products.

The HI755-26 Marine Alkalinity Reagent follows the Colorimetric Method in which the reaction causes a distinctive range of colors from yellow to green to blue to develop. When keeping this reagent you need to store it at room temperature (+15°C to +25°C) (59F-77F) and protect from light and moisture.

Keeping the Alkalinity regent in an aquarium cabinet near a sump is not ideal. It’s very common for the stand of an aquarium to exceed 77F, especially if you are running lights for a refugium, have pumps or other electronic equipment near the reagents. In addition aquarium stands tend to be very humid environments and thus not ideal for storage of reagents. Please keep your reagents in a cool, dry place that doesn’t have great variations in temperature or moisture levels. All of our reagents come with a Safety Data Sheet listed on their product page on our website. If you go to the safety data sheet there will be a section for handling and storage for each reagent.

Finding “chunks” in your HI755-26 reagent is no cause for concern. There are no reportable problems associated with “chunks” and you can gently shake the bottle before use to mitigate any particulates. Should you see "chunks" in your cuvette we recommend letting them settle to the bottom or rise to the top before preforming analysis.

If you have any questions, comments and problems with your reagents or any other Hanna product, please contact [email protected] or call 877-MY-HANNA. We value our customers and strive provide the best experience for your testing needs.

Thank you for the response

 

[Hanna Instruments]

We are happy to help! Thank you for choosing Hanna Instruments for your testing needs.

 

[reefwiser]

Thanks for the reply Hana its what I do every time. One should never store any aquarium supply's in their sump. Test kits additives in bottles or any other types of cleaning materials. They are all points of contamination due to the nature of a saltwater aquarium. Learned this long ago the hard way.

 

[Hanna Instruments]

Thank you for choosing Hanna we really appreciate your support!

 

[DBR_Reef]

I had this same problem- .7 dkh lower with a new bottle and I test every day

 

[Hanna Instruments]

I had this same problem- .7 dkh lower with a new bottle and I test every day

If you notice issues than you can always contact our technical support department, [email protected] and give them your reagent lot number to get any problem solved. There is an accuracy rating of ±0.3 dKH ±5% of reading on the checkers and its best to follow our Best Practices for Using a Hanna Checker. You can also purchase a calibration kit to make sure your Checker is not producing results out of a range of the accuracy. Hope this helps and thank you for using our products!

http://blog.hannainst.com/checker-best-practices

 

[CJBuckeyes]

I have three new bottles, all almost 1 dkh lower than at least the last dozen. I check daily, and my alk hasn't budged in months. I received these three bottles within the last 10 days, and they are stored in a cool, dark place.

@Hanna Instruments do you guys sample every lot? Can everyone who is seeing this alk shift in the new bottles post their lot # here? I will post mine soon..

 

[JonasRoman]

Of course I could be wrong but my opinion is that this method is not accurate enough for our purpose. The accuracy seems to be around +-0.3dKH (I have one myself and compared it to proper titration) but precision is good, thus: the machine do the same thing with repeated measurements but it does it wrong.
Most of the time it measures too high and I think that the error increases little further with higher dKH.
This method is not a titration method but an adding of a constant amount of acid and then via bromocresoolgreen as pH indicator we read the pH by photometric method. The problem with this method is that the pH value is not completely linear to dKH even when we go to a pH below endtitration point 4.2. I guess that the method is based on that principals, that if you titrate a solution with a strong acid (I guess sulphuric acid in this case) so you always with purpose go below the endtitrationpoint for HCO3(thus well below 4.2 pH), then we have almost (but not total) linear relationship between the pH and the alkalinity we had before we started adding acid. But as I said, the relationship is not perfect linear so you cannot perfect direct-translate pH to dKH even in this area of titration-curve. So this is the reason according to my belief why this Hanna checker is not so accurate. If any chemist think this is not correct please give me feedback.

I have done own experiments with this method, thus always adding a constant amount of acid but so much so you always go below pH 4.2 and measured with pH electrode. That is a reasonable linear relationship between dKH and pH in this case but also with the pH electrode there was an inaccuracy at least around 0.2dKH.
And, the higher dKH the inaccuracy was increasing, and that I guess is due to that the pH titration curve when narrowing pH4.2 is definitely not linear anymore.

I guess Hanna chooses this method as it is easy. No titration. Very easy to use. But as I said, we need higher accuracy concerning this important parameter.

My goal is at least +-0.1dKH.

 

[cubbyman60]

@Hanna Instruments
I spoke with customer service today. They were great and super fast. Thank you.

I certainly find my hanna tester to be very precise. If I measure the same sample with the same technique twice in a row I get the same value or +-.1. I'm happy with that. Of course I cannot verify accuracy because I don't know the TRUE alkalinity value.

 

[JonasRoman]

@Hanna Instruments
I spoke with customer service today. They were great and super fast. Thank you.

I certainly find my hanna tester to be very precise. If I measure the same sample with the same technique twice in a row I get the same value or +-.1. I'm happy with that. Of course I cannot verify accuracy because I don't know the TRUE alkalinity value.

I agree with you that precision is nice

If you at least some time compare with a proper titration (Salifert for instance), you can translate the measurements

 

[cubbyman60]

I agree with you that precision is nice

If you at least some time compare with a proper titration (Salifert for instance), you can translate the measurements

Yes, I am confident in the precision.

I was going to say that I could compare with a titration like Salifert. However, that would yield only concordance between the two tests. This definitely would be reassuring and helpful, you are right. But, again, it wouldn't help me determine TRUE alkalinity any better- only that the two tests agree. Worst of all, if they do not show concordance, I wouldn't know which one to trust.

If I don't know which to trust, I appreciate the Hanna checker because it takes my eyes' abilities to verify color change, which is probably the least reliable part of the entire test. I know the reproducibility/precision is there.


EDIT: @JonasRoman
I looked at your thread. Cool project/product. I see that you have good precision with your instrument. It also has high concordance with salifert. But, salifert can be inaccurate as well, no? Hope not to high jack the thread.

 

[Rory's Reef]

Do two test in a row. One test with the old reagent and then one test with the new reagent. Could you tell us your results?

I keep my reagents in a separate cabinet to the side of my tank. I also live in Colorado so I have very little moisture compared to most places. The first pictures is the test with the old reagent that was opened approximately 6 weeks ago. The second picture is the new one that I just opened last night to perform the test. There's always room for some human error and this falls just outside of the ±0.3 dKH range. I think the Hanna Checker is still accurate enough for me for daily readings, but may due a titration test once a week as well.

 

[Centerline]

Of course I could be wrong but my opinion is that this method is not accurate enough for our purpose. The accuracy seems to be around +-0.3dKH (I have one myself and compared it to proper titration) but precision is good, thus: the machine do the same thing with repeated measurements but it does it wrong.
Most of the time it measures too high and I think that the error increases little further with higher dKH.
This method is not a titration method but an adding of a constant amount of acid and then via bromocresoolgreen as pH indicator we read the pH by photometric method. The problem with this method is that the pH value is not completely linear to dKH even when we go to a pH below endtitration point 4.2. I guess that the method is based on that principals, that if you titrate a solution with a strong acid (I guess sulphuric acid in this case) so you always with purpose go below the endtitrationpoint for HCO3(thus well below 4.2 pH), then we have almost (but not total) linear relationship between the pH and the alkalinity we had before we started adding acid. But as I said, the relationship is not perfect linear so you cannot perfect direct-translate pH to dKH even in this area of titration-curve. So this is the reason according to my belief why this Hanna checker is not so accurate. If any chemist think this is not correct please give me feedback.

I have done own experiments with this method, thus always adding a constant amount of acid but so much so you always go below pH 4.2 and measured with pH electrode. That is a reasonable linear relationship between dKH and pH in this case but also with the pH electrode there was an inaccuracy at least around 0.2dKH.
And, the higher dKH the inaccuracy was increasing, and that I guess is due to that the pH titration curve when narrowing pH4.2 is definitely not linear anymore.

I guess Hanna chooses this method as it is easy. No titration. Very easy to use. But as I said, we need higher accuracy concerning this important parameter.

My goal is at least +-0.1dKH.

0.1 sounds great but I don't think there really is a consumer test kit that will yield those results accurately. For years I used the RedSea pro kits as their resolution was supposed to be .05 but I had several bad batches of titration solution and eventually moved to Hanna.

 

[JonasRoman]

0.1 sounds great but I don't think there really is a consumer test kit that will yield those results accurately. For years I used the RedSea pro kits as their resolution was supposed to be .05 but I had several bad batches of titration solution and eventually moved to Hanna.

0.1 is maybe difficult as long as the volume of Salifert is only 4ml but 0.15 is definitely an accuracy goal which you by ease can achieve with salifert as long as you do not destroy the acid by contamination it. The acid in salifert is a little stronger than some laboratory standard "reagents" , I think they use sulphuric Acid of 0.011M instead of a quite common conc of 0.01M as you for instance have in Hach manual test-kit.
The reason of that I guess is to within 1 ml acid have enough range (0-15.6dKH or something like that). That, according to small volume of 4ml will do that the resolution is 0.01ml acid in the syringe which give us a resolution of 0.15dKH.
I have done maybe 500 measurements now with salifert to compare with my machine I develop and can say with quite good self confidence that salifert is extremely reliable. I have never got a wrong batch. I think that if you got an error with salifert you have in some way contaminated the sulphuric acid. For instance the tip of the syringe may never be in contact with anything and absolutely not water etc.
The second issue could be when to read the colour change. I have done several titration with ph electrode down to 4.2 and compared which colour this corresponds to and that is almost the first colour, thus violet, NOT reddish. If you got reddish you have a pH below 4 and thus get false high dKH.
Taken in account these variables I should say Salifert is in worst case accuracy of 0.2 but in correct hands 0.15dKH. The precision is not so sensitive, as you do the same every time if you have the same user, so there I should say 0.15 or better.

I think it wise to always check another method (machine or other methods than titration) with a acid titration.

 

[runzwithscissors]

I keep my reagents in a separate cabinet to the side of my tank. I also live in Colorado so I have very little moisture compared to most places. The first pictures is the test with the old reagent that was opened approximately 6 weeks ago. The second picture is the new one that I just opened last night to perform the test. There's always room for some human error and this falls just outside of the ±0.3 dKH range. I think the Hanna Checker is still accurate enough for me for daily readings, but may due a titration test once a week as well.

I think the human error might be due to those "pale ales" in the background

 

[Hanna Instruments]

A big advantage for using a Hanna Checker is there little subjectivity in the process of analysis. We have a very simplified alkalinity test, there are no color changes to determine or drops to count. This leads to a higher rate of repeatable success and precision . The colorimetric method is a well-established method used by various producers of alkalinity testing equipment. Although it is not a standard method like SM 2320B it still has yielded successful results for hundreds of thousands of reef keeping hobbyists across the globe. We do sell sulfuric acid and high grade pH electrodes/meters so and if a hobbyists chooses they can always titrate with sulfuric acid down to a 4.5 endpoint (which is the EPA method).

http://hannainst.com/0-01-m-sulfuric-acid-1l-hi70458.html

http://hannainst.com/hi12302-halo-ph-electrode-with-bluetoothr-smart-technology.html

Titrate 50mL of water with the 0.01M H2SO4 to pH 4.5 with a calibrated meter. Then, take the mL of titrant used x 1.121= dKH alkalinity. If you have a 7.5 dKH tank, that should be about 8-10mL, meaning the one bottle of $16.00 sulfuric acid will last you for about 100 tests. Alternatively, you could do the titration to pH 4.2, a popular seawater variant.

Thanks for the feedback everyone, we strive to provide the best testing experience for all of our customers and encourage anyone to reach out if they ever have problems with your analytical instruments. Please contact [email protected] or call 877-My-Hanna.

 

[Hanna Instruments]

We Also sell the HI84531 Mini Titrator for measuring Titrable Alkalinity in Water and Wastewater.

http://hannainst.com/hi84531-titratable-alkalinity-mini-titrator-for-water-analysis.html

It can measure in terms of mg/L (CaCO3) or meq/L. It does the pH 8.3 or pH 4.5 method, based on APHA/AWWA/WEF Standard Method 2320B.

The HI84531 incorporates a precision piston style dosing pump that adjusts the volume of dosing dynamically based on the voltage change. This dosing system reduces the amount of time required for the titration while providing for a highly accurate determination of the amount of titrant used.

This mini titrator is supplied complete with all the materials necessary to perform low and high range measurements of alkalinity in water. All chemicals are premixed and prepackaged including standardized titrants, reagents and pump calibration solution. There is no need for volumetric glassware or analytical balances.

 

[Rick.45cal]

The Halo pH pen is pretty slick!

On the mini titrator, how many alkalinity tests (approximately) do you get from 120ml of titrant for 7.5dKH 35ppt seawater? That's a very cool device.

Which range titrant would you be using. High or low range?

 

[NeverlosT]

I have used Hanna checkers for Alkalinity and ULR Phosphorus for years. I will admit I had issues with test complexity and repeatability with the Calcium checker, but the ALK and ULR Phosphorus have been great.

The trick I think with any of these is establishing trends. I test ALK often, and I never make a big change based on one measurement, and always take into account if a new reagent is in use. This will keep you from making knee-jerk reactions that will cause your ALK to swing up and down.

It is good to know that the particulate in the reagent is not an issue!
Good luck!

 

[Hanna Instruments]

The Halo pH pen is pretty slick!

On the mini titrator, how many alkalinity tests (approximately) do you get from 120ml of titrant for 7.5dKH 35ppt seawater? That's a very cool device.

Which range titrant would you be using. High or low range?

The Halo pH electrode is a laboratory grade electrode that does not require the use of a meter, but instead utilzes our Hanna Lab app to display readings on a smart phone or tablet. You can log pH/temperature readings and even calibrate to up to 5 points for increased accuracy.

For titrant we recommend the low range in this case, 7.5 dKH*17.848 (conversion for ppm CaCO3)= ~133.86ppm. You can most likely get 30-40 tests from one bottle in your case.