I'm confused by PH and probes and calibration and ...

[RonS]

Background;
- New tank, Waterbox 220.6, cycling. No water changes to date, tank has been wet for a couple weeks.
- All dry Marco rock going in.
- Using the APEX conductivity and Ph probes
- Tank between 78-79 degrees
- Used Kent Reef Salt Mix, https://www.kentmarine.com/products/sea-salt.htm
- Just a couple green chromis in the tank at this point
- Recalibrated the Apex probes using recently purchased calibration solution packets
- Skimmer running (although not doing much other than aerating the tank at this point). Windows have been open, don't think its a CO2 issue.

When I filled the tank originally, I took out my calculator computed how much salt I would need. The salt measurement has always been nearly correct, currently showing 34.4. My PH measurement always shows 7.82 instead of the 8.2 I would expect from the packaging.

Am I missing something obvious? My instinct is that the probe (and calibration procedure?!) must be off, but I repeated the experiment of recalibrating twice. I tried to double check everything with a Red Sea test kit. My best guess from the eye color Rorschach tests were that ALK=7.98 and PH=8.2. So I guess that means my probe is kaput? It is 3-4 years old, from an old tank, was unused the last 16 months because, life.

Thanks!

 

[ReefRusty]

Background;
- New tank, Waterbox 220.6, cycling. No water changes to date, tank has been wet for a couple weeks.
- All dry Marco rock going in.
- Using the APEX conductivity and Ph probes
- Tank between 78-79 degrees
- Used Kent Reef Salt Mix, https://www.kentmarine.com/products/sea-salt.htm
- Just a couple green chromis in the tank at this point
- Recalibrated the Apex probes using recently purchased calibration solution packets
- Skimmer running (although not doing much other than aerating the tank at this point). Windows have been open, don't think its a CO2 issue.

When I filled the tank originally, I took out my calculator computed how much salt I would need. The salt measurement has always been nearly correct, currently showing 34.4. My PH measurement always shows 7.82 instead of the 8.2 I would expect from the packaging.

Am I missing something obvious? My instinct is that the probe (and calibration procedure?!) must be off, but I repeated the experiment of recalibrating twice. I tried to double check everything with a Red Sea test kit. My best guess from the eye color Rorschach tests were that ALK=7.98 and PH=8.2. So I guess that means my probe is kaput? It is 3-4 years old, from an old tank, was unused the last 16 months because, life.

Thanks!

Are your PH measurements done via manual test or is thia through the Apex? If your reading 8.2 manual I would say your Probes are faulty.

Have a read of this?

New Apex - pH and conductivity probes

Hi y'all, I am new to Apex. I got a brand new Apex 2016 and started setting it up last night. I am having an issue with the pH and conductivity probes. When I tried to calibrate the pH probe, the iPhone app hung up and I could not complete the calibration with the first reference...

forum.neptunesystems.com

 

[robbyg]

A 3 year old pH probe is a dead probe!
I replace mine at about the 18 month mark.

 

[RonS]

Thanks for the feedback! I tried again last night and ended up in the same place. What is extra confusing is that after calibration flipping back and forth between 7 and 10 solutions reads correctly, but in the tank its still off from what logic (and RedSea) says it should be.

Guess I'll order another probe, cyber monday and all.

Cheers!

 

[Randy Holmes-Farley]

Thanks for the feedback! I tried again last night and ended up in the same place. What is extra confusing is that after calibration flipping back and forth between 7 and 10 solutions reads correctly, but in the tank its still off from what logic (and RedSea) says it should be.

Guess I'll order another probe, cyber monday and all.

Cheers!

It would be absolutely nutso for any manufacturer to claim what the pH of new salt water will be once mixed in your home. ALL that they can do is say what the mix itself would do if there was absolutely zero aeration, and that is presumably what they claim.

pH is determined by the alkalinity and the CO2 level in the water, which after mixing will be, at least partly driven by the CO2 level in your home air.

So do not take the package claim to mean anything at all, especially that you are not calibrated properly.

i discuss pH calibration issues in detail here:

Aquarium Chemistry: Measuring pH with a Meter

This article describes how pH meters work, how to select one to use, and how to best use it to measure the pH of a reef aquarium.

reefs.com

 

[Randy Holmes-Farley]

Thanks for the feedback! I tried again last night and ended up in the same place. What is extra confusing is that after calibration flipping back and forth between 7 and 10 solutions reads correctly, but in the tank its still off from what logic (and RedSea) says it should be.

Guess I'll order another probe, cyber monday and all.

Cheers!

I would not assume there is a probe issue if it calibrates properly.

 

[RonS]

Ha! Thank you for the replies, Randy, and the pointer to the article. On first read I'm definitely in a bit over my head on the details, I'll have to read it a couple times before it all sinks in.

But you've given me good data to work with, and the article has a couple good tips that I wasn't following (3/4/5/). I'll do some further experimentation, likely starting by borrowing a second probe and comparing apples/apples.

One further question, the link in the referenced article to your other article "Solutions to pH Problems by Randy Holmes-Farley Advanced Aquarist, June 2002 http://www.advancedaquarist.com/2002/6/chemistry" (footnote #1) cannot be found, I assume because that site has been reorganized. Would you happen to have an alternate pointer or export?

Cheers! Stay safe everyone,

 

[Randy Holmes-Farley]

Ha! Thank you for the replies, Randy, and the pointer to the article. On first read I'm definitely in a bit over my head on the details, I'll have to read it a couple times before it all sinks in.

But you've given me good data to work with, and the article has a couple good tips that I wasn't following (3/4/5/). I'll do some further experimentation, likely starting by borrowing a second probe and comparing apples/apples.

One further question, the link in the referenced article to your other article "Solutions to pH Problems by Randy Holmes-Farley Advanced Aquarist, June 2002 http://www.advancedaquarist.com/2002/6/chemistry" (footnote #1) cannot be found, I assume because that site has been reorganized. Would you happen to have an alternate pointer or export?

Cheers! Stay safe everyone,

The online magazines periodically change the URL, but they can always be found either by googling the article name, or by using the internet archive/way back machine on the URL.

Here is this one (which is 18 years old):

Chemistry And The Aquarium: Solutions To pH Problems

This article provides a series of solutions to common pH problems in aquaria, and should permit most aquarists to diagnose and solve the pH problems that may arise in their own tanks.

reefs.com

and a more recent pH article of mine:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/