Alkalinity testing methods

Frikkie · Sep 20, 2017

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 · Sep 20, 2017

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

Frikkie · Sep 20, 2017

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 · Sep 20, 2017

Frikkie said:
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 · Sep 20, 2017

Check the last page[emoji1303]

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

TbyZ · Sep 20, 2017

Frikkie said:
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 · Sep 20, 2017

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 · Sep 20, 2017

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 · Sep 20, 2017

Thanks Randy that was exactly what i was looking for!

Randy Holmes-Farley · Sep 20, 2017

You're welcome.

Happy Reefing.

Hanna Instruments · Sep 20, 2017

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 · Sep 20, 2017

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

Randy Holmes-Farley · Sep 20, 2017

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

What do they use?

JimWelsh · Sep 20, 2017

Randy Holmes-Farley said:
What do they use?

The method is colorimetric.

Frikkie · Sep 20, 2017

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

Hanna Instruments · Sep 20, 2017

Frikkie said:
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 · Sep 20, 2017

Frikkie said:
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 · Sep 20, 2017

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.