Can't calibrate Apex pH probe

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jasonrusso

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I have 2 tanks. I noticed that the pH was staying steady at 8.17 on my reef tank which I know isn't right. The probes are old 4-5 years so I know they are outside the normal lifespan, but they seem to read correctly up until now so I never worried too much about it.

I figured I would calibrate them because I haven't done it for some time. I had a PITA time calibrating the reef tank probe because the reading was not changing in the different calibration pouches. I figured the probe was just dead.

On my FOWLER, the probe read 8.2 in the 7.0 solution and 10 in the 10 solution. This put the tank water reading at 7.3 pH which I know isn't correct. It was reading 8-8.2 before.

I bought 2 probes on Amazon. I got gel filled Milwaukee double junction probes (I bought good ones so I thought). I got the new probes in yesterday.

I still couldn't calibrate the reef tank. I figured out that the PM1 was bad so I swapped it out for a spare I had. I am still not happy with the calibration results. The probe reads around 750 in the 7.0 and 1060 in the 10. It puts the pH around 7.8.

The fowler is worse, the new probe reads like 820 in the 7.0!

Either way, the Milwaukee probes are going back and I bought the BRS double junction probes which I had in my FOWLER for the last 4-5 years without a problem.

Do I need to reset the PM1 somehow? And I confirmed that they are reading incorrectly by doing a manual dropper test.
 
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lapin

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you are doing this correct
 

BoxKing

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Should you be calibrating with the TC saved prior to running, or is TC correction only necessary for Salinity?
My PH is roughly .13 off from my Hanna, and has kept up with the increase PH readings from my recent install of a CO2 scrubber- as long as both are within the same range it wont bother me, but Id rather know if the TC factor (which I used) plays any role.
 
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jasonrusso

jasonrusso

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Should you be calibrating with the TC saved prior to running, or is TC correction only necessary for Salinity?
My PH is roughly .13 off from my Hanna, and has kept up with the increase PH readings from my recent install of a CO2 scrubber- as long as both are within the same range it wont bother me, but Id rather know if the TC factor (which I used) plays any role.
TC? Temperature correction? I have the temperature correction turned on. I also put the calibration packets in the sump to match the temperature
 

BoxKing

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I ran my calibration the same way. Even placed the probe back into the 7.01 solution with proper a reading. Once I put it back in to my tank my readings were off 7.67. I tested the same calibration solutions with my Hanna, then the tank water with a reading of 7.78…

Tested moments ago Apex 7.83. Hanna 7.97 - now the spread is getting greater. My PH on both probes has gradually increased, and now stable- currently only running one of my skimmer air inlets to the Scrubber, with a Y connector to hook up the other tomorrow. I assume my PH will take another spike within a day or two after I make both connections (Jump400 skimmer). I may try my hand at final calibration once I see the numbers rise, and flatten out - possibly do this with Apex support. If that doesn’t work, Ill just graph my numbers over the course of a week or two, and do self correction to the Apex readings

Why couldn’t they make all the probes with a manual calibration like Temp…. ? PIA
 
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hllb

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Any ideas on this issue? I'm having a similar issue. My probe has always run low compared to my salifert test, but after updating the AOS today, it's crazy all over the map and super low compared to Salifert.
 
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jasonrusso

jasonrusso

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Any ideas on this issue? I'm having a similar issue. My probe has always run low compared to my salifert test, but after updating the AOS today, it's crazy all over the map and super low compared to Salifert.
I bought the probes from BRS (the same one I had before), and calibrated 3 times. It is much lower than it was reading before. Now the reef tank is 7.75 at night to 8.01 a few hours after the lights are on.

The fowler stays around 7.85.

Both were above 8.0 before.
 
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