How does Hanna Alk Kit work?

[Kerbash]

Hey,

Im just wondering does anyone know how the Hanna Alk checker work? Chemically? As I understand it alkalinity is the tolerance to the change in pH, but the hanna checker only reads the spectrum from control seawater (no regent added) and the final one after the reagent are already added. So how does it check for the initial pH of the water? Does it just guess? Does that mean its inaccurate?

Thanks

 

[OfficeReefer]

Hmm, perhaps I am confused but this is an electronic colormetric tester?

It works based on Beer-Lambert law.

Colorimeter - Beer’s law, Lambert’s law, Principle, Working with FAQs

Colorimeter - A colorimeter is a device that is used in Colorimetry. It refers to a device which helps specific solutions to absorb a particular wavelength of light. For colorimeter uses and more click here.

byjus.com

 

[Kerbash]

Hmm, perhaps I am confused but this is an electronic colormetric tester?

It works based on Beer-Lambert law.

Colorimeter - Beer’s law, Lambert’s law, Principle, Working with FAQs

Colorimeter - A colorimeter is a device that is used in Colorimetry. It refers to a device which helps specific solutions to absorb a particular wavelength of light. For colorimeter uses and more click here.

byjus.com

I failed pH math in school so don't quote me But I thought that alkalinity is the measurement of multiple ions and their interaction and how they sorta prevent the pH from changing? Don't the colorimetric test only work if you know specifically which substance you are looking for? Or if it is colorimetric, would you happen to know which chemical they used to mark the ions?

Edit: I have no clue if this is right but I initially thought that they used bromothymol blue dye (cuz I always see green - blue purely guess work) with some acid and use the spectrometer to measure the current pH.

 

[ZoWhat]

The powder in the packet is pixie dust.

It's Magic

 

[Kerbash]

The powder in the packet is pixie dust.

It's Magic

no wonder why is so expensive...

 

[Randy Holmes-Farley Verified Community Expert]

You add acid and an indicator dye (or more than one). The pH attained is an indication of the alkalinity.

 

[Kerbash]

You add acid and an indicator dye (or more than one). The pH attained is an indication of the alkalinity.

Not sure if my understanding is correct but to get alk, dont you need pH at two points? But the hanna kit only takes one read with the indicator dye. Im just confused how it can get the initial pH.

 

[Randy Holmes-Farley Verified Community Expert]

Not sure if my understanding is correct but to get alk, dont you need pH at two points? But the hanna kit only takes one read with the indicator dye. Im just confused how it can get the initial pH.

No, although the method Hanna uses may not be especially accurate as the pH or alk deviate significantly from NSW values, while the normal titration method is not impacted by these.

https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lom3.10253

"The one-point titration method using BPB was utilized at a remote field location, One Tree Island, Australia and was found to be suitable for producing accurate and precise alkalinity data in a timely manner; ∼ 10–15 samples can be determined per hour. "

 

[Kerbash]

ic thank u, thanks for the paper too btw

 

[Frank SM]

I would say use with caution. My Hanna Alk checker worked great, until it didn't. It started giving me artificially high results. By the time I realized it, my Alk was in the 6's. My tank took a huge hit. I now use the pH titration method.

 

[Kerbash]

I would say use with caution. My Hanna Alk checker worked great, until it didn't. It started giving me artificially high results. By the time I realized it, my Alk was in the 6's. My tank took a huge hit. I now use the pH titration method.

Yeah, i switched over like 2 months ago from my salifert test kit, it did give me a weird reading, from ~8 in the titrating one to 10 dkh with hanna. Good to know the titration one is more accurate.

 

[Tuan’s Reef]

Yeah, i switched over like 2 months ago from my salifert test kit, it did give me a weird reading, from ~8 in the titrating one to 10 dkh with hanna. Good to know the titration one is more accurate.

I got the Hannah alk just so i can complete my 3D printed tray lol I only used it once. I use Salifert exclusively for ALK.
The other 2, I use very often.