pH probes calibration off point

[BonelessEvil]

I've calibrated both Neptune systems and BRS brands of probes (double junction, using Apex automatic calibration). Having given up on my original Neptune systems probe, as it seemed to have a faulty cable (the reading would match my test kit, then it wouldn't, almost like a faulty cable was at play). As for the 2nd probe, the BRS (brand-new as of last week), I've not been able to get it to match the Red Sea test kit I used: BRS = 7.7, Red Sea test kit = 8.0.

What is considered a reasonable margin of error for a pH probe?
should I use manual calibration? Will that help?
Should I start over, cleaning the probe off and then calibrating? Instructions on cleaning the probe would be helpful

 

[Hitman]

Cleaning I just use a soft toothbrush and rodi water.
Calibration I found manual works better, and log into apex.local don't to it through fusion.

 

[BonelessEvil]

what's the difference between fusion and apex.local in this regard?

Cleaning I just use a soft toothbrush and rodi water.
Calibration I found manual works better, and log into apex.local don't to it through fusion.

 

[Hitman]

what's the difference between fusion and apex.local in this regard?

For some reason doing through fusion I’ve not had a solid calibration stick, doing it through apex.local I’ve alwats been dead on even weeks later.