2 Apex reporting different specs in the same system... (Temp and pH)

[Jesse Sunday]

HI All!

TL;DR: Why would an Apex Jr and Apex Pro report pH numbers that are ~.20 different and Temp ~0.8 different? Am I worrying over nothing? Is that variance normal?

Here's the long version.

I installed a new Apex Jr system in my 90g tank a few days ago, went through the pH calibration, etc., and all seemed fine. Then, I ended up getting another brand-new (sealed) Apex Pro yesterday.

The pH manual calibration on the Pro kept failing on the 10 solution. Repeatedly. Automatic calibration would usually complete. I even tried different solution and it would still fail on the 10. I swapped the Jr pH probe and the Pro probe between systems and re-calibrated both. (the second pH probe still gives calibration issues even on the Jr system)

All probes are in the same rack in the sump of the Reefer 350 so there should be no variance.

Am I being ridiculous to want the pH to be closer than 0.2 off? Am I driving myself crazy or should I contact Neptune?

Thanks for helping me work through my OCD.

 

[Joekovar]

Calibration is typically a temperature dependant operation. If the temperature accurately is off, that will cascade to other measurements.

 

[Jesse Sunday]

Calibration is typically a temperature dependant operation. If the temperature accurately is off, that will cascade to other measurements.

Ohhhhh, interesting.

I have "TC" turned off, should I turn it on and re-calibrate?

 

[Dburr1014]

Same with PH.
Is all in the calibration.

 

[iReefer12]

Both temp and ph probes need calibrating it seems.

 

[Jesse Sunday]

Both temp and ph probes need calibrating it seems.

That's the thing, I've tried calibrating the pH probes many times. (the newer probe is the one that fails the manual calibration so I'm thinking it might be faulty)

I'll try again today with the "TC" Temperature Compensation" turned on.

 

[iReefer12]

I had an old temp probe that sat in storage for years, plugged it in and it read about 1.5* higher than the other 2 probes in the same system. I got a glass thermometer (supposed to be the most accurate way to measure temp, the old fashioned way). Confirmed the other temp probes were correct and then just calibrated the one that’s off and set it to the same temp as the other 2.

 

[iReefer12]

On the ph probe, if it’s not new, it could be a problem with the probe.

 

[Jesse Sunday]

On the ph probe, if it’s not new, it could be a problem with the probe.

They're both brand new.

 

[Jesse Sunday]

So based on the Temp / pH correlation mentioned above... I calibrated my temp probes to within 0.2 of each other... then I turned on "Temp Compensation" (TC) in the Advanced settings and recalibrated both pH probes on both Apex systems.

As I suspected, the one Probe is still about .2 to .37 off.

(seen below showing 10.20 while sitting in the 10.00 soultion and 7.37 in the 7.0 soultion)

Should I request another pH probe from Neptune, or just live with knowing that one probe (the Jr system will eventually live in a different tank) is ~0.27 higher?

 

[Dburr1014]

I always do 2 calibrations back to back on my pH in the manual setting of apex.
I always find they are not very accurate the first time and usually time out.
Not sure why but it helps.

 

[Jesse Sunday]

I always do 2 calibrations back to back on my pH in the manual setting of apex.
I always find they are not very accurate the first time and usually time out.
Not sure why but it helps.

I even soaked the probes for several hours in 7.0 before I installed them, as suggested by Neptune. And did maaaaaaany calibrations. The Manual ones would usually fail on the 10.00 portion.

Not sure why. I even tried different solutions, thinking the 10.00 from Apex was "bad."

Oh well, I think I will live with them being "off" since they're eventually going into different tanks.

 

[SpyC]

Was your temp probe also soaking in the same temp liquid whilw the ph probe soaked? I think you need to have the temp probe at the same temp as the fluid or else it won't calibrate properly. I let my calibration packets sit in the same water as my temp probe for about 30 minutes, then do the ph calibration.

Regarding the new probes, I would definitely push for replacement parts of any product if issues are being experienced after multiple troubleshooting attempts

 

[n2585722]

If you have new pH probes let them stay in the tank a few days and then recalibrate. New pH probes tend to drift after they are removed from the storage fluid and placed in the tank. I don't calibrate new probes for a few days after placing them in the sump. I don't use Apex but this happens on all the pH probes I have used to a degree. Even at that they are not going to read exactly the same. Sometimes they might but don't expect it all the time but they should be close. Also they will slowly drift with time and have to be recalibrated but they may not drift the same.