Alkalinity testing methods

[Frikkie]

Hi everyone,
With all the buzz of alkalinity monitors and all the methods they use to test alkalinity, I was wondering if someone could explain how they use ph probes to measure alkalinity?

Thank you!

 

[TbyZ]

I thought they all employed a titration test to measure alk?

 

[Frikkie]

Im referring to the new kh lab, in their thread they stated that they use a ph probe in the latest iteration. That is what i am wondering about.

 

[TbyZ]

Im referring to the new kh lab, in their thread they stated that they use a ph probe in the latest iteration. That is what i am wondering about.

got a link?

 

[Frikkie]

Check the last page[emoji1303]

https://www.reef2reef.com/threads/kh-lab-module-for-kore-5th.296410/

 

[TbyZ]

Check the last page[emoji1303]

https://www.reef2reef.com/threads/kh-lab-module-for-kore-5th.296410/

Pacific Sun HQ says-
kH Lab is using different method for alkalinity measuring. We are not using pH electrode what make that device more stable and precise in long time(in compare to device with pH probe which need to be calibrated much more often).

Keiffer the reefer says-
Thanks for the photo! Is that a pH probe I see? Your first post said no pH probe.

Pacific Sun HQ says-
Yes, it's pH probe.
=======================

makes no sense to me. But they claim not to use a pH probe on their calcium reactor.

The pH probes would be to merasure pH, nothing else.

 

[reefwiser]

pH sensors measure the level of pH in sample solutions by measuring the activity of the hydrogen ions in the solutions. This activity is compared to pure water (a neutral solution) using a pH scale of 0 to 14 to determine the acidity or alkalinity of the sample solutions.

This is also how all alk test work. There is a colormetic version of the ph to alk test also.

 

[Randy Holmes-Farley Verified Community Expert]

In an alkalinity determination you add acid until the pH is about pH 4.2 or so. An alk titration kit just uses a pH-sensitive dye instead of a pH meter to "know" when the pH has reached that endpoint..

I show how to do that yourself here:

A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
https://www.reef2reef.com/blog/a-diy-alkalinity-test-by-randy-holmes-farley

 

[Frikkie]

Thanks Randy that was exactly what i was looking for!

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing.

 

[Hanna Instruments]

Here are some supplies we carry for such a task.

HI70458- Sulfuric Acid 0.01M, 1L
http://hannainst.com/0-01-m-sulfuric-acid-1l-hi70458.html

HI12302- HALO® Wireless Field pH Meter
http://hannainst.com/hi12302-halo-ph-electrode-with-bluetoothr-smart-technology.html

HI181- Compact Magnetic Mini-Stirrers with Electrode Holder
http://hannainst.com/hi181-compact-magnetic-mini-stirrers-with-electrode-holder.html

 

[JimWelsh]

Neptune Trident does not use a pH electrode for its alkalinity titration endpoint determination.

 

[Randy Holmes-Farley Verified Community Expert]

Neptune Trident does not use a pH electrode for its alkalinity titration endpoint determination.

What do they use?

 

[JimWelsh]

What do they use?

The method is colorimetric.

 

[Frikkie]

Wonder why they went with colorometric, titration seems like an easier and more accurate method?

 

[Hanna Instruments]

Wonder why they went with colorometric, titration seems like an easier and more accurate method?

no pH electrode maintenance for one, successful alkalinity titration via pH electrode requires proper care/calibration in order to function correctly. Also Calcium and Magnesium are not measured with pH electrodes, but all three can be done with colorimetry

 

[JimWelsh]

Wonder why they went with colorometric, titration seems like an easier and more accurate method?

It is a titration. The endpoint detection method is colorimetric. The two are not mutually exclusive.

 

[Randy Holmes-Farley Verified Community Expert]

Jim or Hanna, have you guys seen any good data on how the pKa of the dyes chosen for these sorts of experiments change between freshwater and seawater? I've never seen such data published.

 

[JimWelsh]

DOI: 10.1016/0304-4203(89)90061-3

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Jim.