How Often do You Change Your GHL pH Calibration Solutions?

Dr. Jim · Nov 1, 2020

I'm thinking it may be time to buy new ones because I'm getting whacky results with my KH Director and my pH probe as well. My solutions are 10 months old and I use them about once a month. My procedure is to clean the probes well: rinse and wipe with RO/DI followed by a 5 min soak in electrode cleaner, followed by another RO/DI rinse and then dry the probe before placing into a calibration solution. I also use a microfiber clothe to slide between the bulb and inner portion of the plastic sleeve.
I place the probe directly into the bottle for the calibration.

Just wondering how often others change the solutions and it you have any interesting techniques.

Thanks!

Lasse · Nov 1, 2020

I only use the same calibration once. Pour it out after using it. I use around 5 -10 ml in each calibration. Use a sample tube - enough wide to house the probe.

Sincerely Lasse

elic173 · Nov 1, 2020

That electrode cleaner sounds interesting. Any details on where I can get it? Do you use that on all your probes?
I just soak mine in citric acid 5%

Dr. Jim · Nov 1, 2020

elic173 said:
That electrode cleaner sounds interesting. Any details on where I can get it? Do you use that on all your probes?
I just soak mine in citric acid 5%

I think it costs around $14 from BRS or Hanna. You are not supposed to use it on the temperature or conductivity probes, just the pH (including KH Director) and Redox probes.

elic173 · Nov 1, 2020

Dr. Jim said:
I think it costs around $14 from BRS or Hanna. You are not supposed to use it on the temperature or conductivity probes, just the pH (including KH Director) and Redox probes.

Thanks!!

chema · Nov 2, 2020

Never reuse the calibration buffer. Do the calibration as recommended by Lasse. That is the rigth way to do it.

Lasse · Nov 2, 2020

I have done a floating device in order to get the right temperature too. Important when calibrating the salinity probe

I fill with calibration liquid and place it in the sump

Sincerely Lasse

chema · Nov 2, 2020

Lasse said:
I have done a floating device in order to get the right temperature too. Important when calibrating the salinity probe

I fill with calibration liquid and place it in the sump

Sincerely Lasse

Simple and effective!

robbyg · Nov 5, 2020

I am not using a GHL system but the process is the same on most controllers. I gave up on those containers of calibration fluid years ago. For roughly the same price you can get pinpoint 7 and 10 packets that are one use.
I buy them in boxes of ten or twenty and each one is fresh when you open it.

CEReefer · Nov 5, 2020

robbyg said:
I am not using a GHL system but the process is the same on most controllers. I gave up on those containers of calibration fluid years ago. For roughly the same price you can get pinpoint 7 and 10 packets that are one use.
I buy them in boxes of ten or twenty and each one is fresh when you open it.

GHL’s KHD uses Ph4 and Ph7, do you think I could use Hanna’s Ph 4.01 and Ph7.01 just fine?

robbyg · Nov 5, 2020

CEReefer said:
GHL’s KHD uses Ph4 and Ph7, do you think I could use Hanna’s Ph 4.01 and Ph7.01 just fine?

Yep it should not be a probleml. Not sure why you would want to use Hanna when Pinpoint has 4.000 and 7.000 fluid for like $1 a pack.

CEReefer · Nov 5, 2020

Because I stupidly bought a giant case of them..

robbyg · Nov 5, 2020

CEReefer said:
Because I stupidly bought a giant case of them..

It happens

When I got my first controller I bought two huge bottles of pH 7 and 10 fluid and then read the label and realized they expired within about two months. That was like $28 down the drain.
I am also very weary of Hanna Reagent refills. They should have a 2-3 year life but sometimes I get ones from dealers that have a date that is 6 months from expiry. The lesson learned is always buy reagents from the big dealers who have fast moving inventory.