pH probe calibration is puzzling me

[Mr_Mocha]

I've been having trouble with my kH director this last week, the previous two weeks it seemed to be working like clockwork.
Results matching up with salifert test results. I know this isn't always the case.

Suddenly one evening it dropped to readings of 5.0dkh and stayed there each test for a couple of days, salifert reading still saying 7.5 each time, even on new test kit.

Next I started getting titration error, then reading of 0dkh [emoji53]

I've been going through the process of remeasurement and calibration with all pumps and the pH probe.

The pH probe readings are back to front, now I am really getting confused [emoji2962]

In the calibration fluid pH 4, actual value pH electrode reads 7.1

In calibration fluid pH 7 I get 7.2

Trust me I have them the right way round, I've treble checked before posting this and making my self looking even more of an idiot.

Is my pH probe knackered?

Any help would be greatly appreciated.

Craig

 

[Jay Z]

Anyway to check they actually put 4.0 in that bottle? Maybe they put the wrong juice in it?

 

[Mr_Mocha]

The colours certainly match up to those displayed on their website

 

[Mr_Mocha]

I suppose I could switch them and calibrate, see what results I get [emoji85]

 

[Jay Z]

I saw that. Just real weird your getting 7 from both.

If it was my probe, I would clean it and try again. If it still came up the same I'd ph test the sample to make sure its lower than 7. If both those didn't do anything, I'd call the probe buggered.

I clean my probes with some vinegar water for 20 minutes, scrub with old tooth brush, soak another 5-10 minutes, brush again, rinse in clean water twice.

My orp probes get dirty with my ozone and I have to clean them every 4 weeks or so. Never had a issue like this with my ph.

 

[Jay Z]

I suppose I could switch them and calibrate, see what results I get [emoji85]

I was just wondering if the 4 was the right color but maybe it had a ph of 7.

I only said that because when I was struggling to calibrate my ph probe, each test pack could very from 7 to 7.2. That was neptune calibration packs.

Not sure on the ghl, but on the neptune kits it was extremely important to have the sample the same temp as the tank water.

 

[Mr_Mocha]

I've tested the pH of each liquid with my pH pen and they're both exactly as they should be. So it's not down to the actual liquids [emoji848]