Apex pH reading high.

[kdtorgy]

I just installed my Apex, calibrated my pH probe with the tasks and it is reading 8.6. This seamed high so I checked with an API and Hanna test kit and got 8.1 and 8.0, respectively. Temp and ORP probes working fine. Any suggestions?

 

[Sean Clark]

Silly questions but...
Did you rinse your probe in rodi water and pat it dry after every wet step? As in removal from saltwater and prior to the 7 solution, after the 7 solution and prior to the 10 solution?
Did you have your calibration solutions tempratue acclimated to the measurement reference sample? So did you have the reference solutions at the same temperature as the tank for the calibration?
Do you have your pH probe connected directly to the Apex base unit or is it connected through a PM1 module via aquabus?

When you say:

Temp and ORP probes working fine.

What are you basing that on? Did you calibrate those too; do you have other test that validate those probe results?

 

[brmc1985]

I just installed my Apex, calibrated my pH probe with the tasks and it is reading 8.6. This seamed high so I checked with an API and Hanna test kit and got 8.1 and 8.0, respectively. Temp and ORP probes working fine. Any suggestions?

Make sure there are no air bubbles where the probe is. If that doesn’t work calibrate again.

 

[Layton (OR)]

I experienced issues calibrating salinity and pH probes my first go around. After doing a bunch of reading and watching some videos, it seems the culprit was air bubbles around the probe. Bought some of these, https://www.bulkreefsupply.com/brs-ph-orp-probe-tip-soaker-bottle.html and filled them with calibration fluid, turn them upside down and no more bubbles. Same issue when I was placing in the sump, so I put them at an angle and give them a little shake before sliding them into the probe holder. Big shout out to Suncrest Reef, that guy has written a ton of useful info that has save me hours of troubleshooting.

 

[kdtorgy]

Silly questions but...
Did you rinse your probe in rodi water and pat it dry after every wet step? As in removal from saltwater and prior to the 7 solution, after the 7 solution and prior to the 10 solution?
Did you have your calibration solutions tempratue acclimated to the measurement reference sample? So did you have the reference solutions at the same temperature as the tank for the calibration?
Do you have your pH probe connected directly to the Apex base unit or is it connected through a PM1 module via aquabus?

When you say:

What are you basing that on? Did you calibrate those too; do you have other test that validate those probe results?

Good questions. Yes I did clean with DI water and shook water off but didn't pat dry. It's possible that the small amount of water left on the probe affected the relatively small amount of buffer solution. I didn't have the calibration solutions at the same temp as the tank but 10 degrees will not cause a pH shift this big. Yes, the probe is directly connected to the base unit. I will recalibrate today making sure to wash and pat dry the probe between steps. Just out of an abundance of caution, I will float the calibration solutions in the tank before calibration and watch for bubbles.

I stated that the temp and ORP probes seem to be working because they are giving reasonable values. The temp probe was reading the same as a wireless temp probe I had been using and the ORP probe stated reading just above 200 and was steadily increasing. Some research I've done seems to agree with this trend and Apex states that an accurate reading will take several days. Is the a reference solution I can check ORP against?

Thanks for the clarifying questions.

 

[kdtorgy]

I experienced issues calibrating salinity and pH probes my first go around. After doing a bunch of reading and watching some videos, it seems the culprit was air bubbles around the probe. Bought some of these, https://www.bulkreefsupply.com/brs-ph-orp-probe-tip-soaker-bottle.html and filled them with calibration fluid, turn them upside down and no more bubbles. Same issue when I was placing in the sump, so I put them at an angle and give them a little shake before sliding them into the probe holder. Big shout out to Suncrest Reef, that guy has written a ton of useful info that has save me hours of troubleshooting.

Good advice. I will recalibrate today using a glass beaker so I can be sure there are no air bubbles on the probe tip.

 

[Sean Clark]

You can get references solutions for ORP.

I only brought up the temp and ORP to highlight the conformation bias that we all have while testing or taking measurements.
If we get the result we are looking for or the result seams reasonable then we take the results and run with them.
Only when we get an unexpected result do we dig deeper and attempt to verify the results.

A good example of this conformation bias for me was my temp probe. It had drifted up 4.1 degrees over time. I never verified that it was accurate. I just trusted it. I thought my temp was climbing because it was summer time when it was actually the probe drifting up slowly over time. The numbers seemed reasonable but they were not accurate. Only when they started going over 82 degrees did I even think to verify the probs accuracy. My tank was 78 the whole time.

 

[Layton (OR)]

You can get references solutions for ORP.

I only brought up the temp and ORP to highlight the conformation bias that we all have while testing or taking measurements.
If we get the result we are looking for or the result seams reasonable then we take the results and run with them.
Only when we get an unexpected result do we dig deeper and attempt to verify the results.

A good example of this conformation bias for me was my temp probe. It had drifted up 4.1 degrees over time. I never verified that it was accurate. I just trusted it. I thought my temp was climbing because it was summer time when it was actually the probe drifting up slowly over time. The numbers seemed reasonable but they were not accurate. Only when they started going over 82 degrees did I even think to verify the probs accuracy. My tank was 78 the whole time.

This falls into the tried and true, "trust but verify" camp. It has always served me well in this hobby.

 

[Sumo Reef]

I recently corrected this for my own Apex. Do you have TC enabled? The temp probe reading on the Apex effects PH reading.

Please see this post. Helped me get my apex readings in line with secondary and thirdary tests

https://www.reef2reef.com/threads/a...ex-salinity-calibration-and-tc-factor.718971/

 

[Dburr1014]

I just installed my Apex, calibrated my pH probe with the tasks and it is reading 8.6. This seamed high so I checked with an API and Hanna test kit and got 8.1 and 8.0, respectively. Temp and ORP probes working fine. Any suggestions?

I have herd also numerous times the task menu is not the way to go. Do it manually thru the Apex, you will get a better reading.

 

[kdtorgy]

I recently corrected this for my own Apex. Do you have TC enabled? The temp probe reading on the Apex effects PH reading.

Please see this post. Helped me get my apex readings in line with secondary and thirdary tests

https://www.reef2reef.com/threads/a...ex-salinity-calibration-and-tc-factor.718971/

Yes, I do have temperature correction enabled. I just recalibrated again and the pH is reading 7.7 which seems about right for this time of day as my lights are still ramping up. I will watch it over the next 24 hours and recheck agains Hanna tomorrow.

 

[ZombieEngineer]

I have herd also numerous times the task menu is not the way to go. Do it manually thru the Apex, you will get a better reading.

This. Automatic always settles too fast on the pH. I always do it manual and just wait 5 minutes in each solution.

Also, float the probe packets in your sump, and watch out for bubbles.

When calibration is complete, check the pH in each packet. If the value is more than 0.03 off in either, recalibrate.

 

[kdtorgy]

This. Automatic always settles too fast on the pH. I always do it manual and just wait 5 minutes in each solution.

Also, float the probe packets in your sump, and watch out for bubbles.

When calibration is complete, check the pH in each packet. If the value is more than 0.03 off in either, recalibrate.

Got it. I did automatic and it was reading the pH 10 solution as 10.0 but the 7 solution as 7.2. I’ll do a manual calibration tomorrow