PH Probe question

[pk1]

Happy Friday Randy!

I have 2 PH meter's, one a Milwaukee and the other a pinpoint. The Milwaukee probe is about 3 months old, and I am not sure on the pinpoint as it was bought used, though it was stated at 3 months also and still wet when purchased. The Milwaukee always seemed to read correctly, until about a week ago--I look at it and it said 7.6, after just an hour or so earlier said 8.3. Not sure what happened to that one. The Pinpoint has read .2-.3 higher consistently, and did not change when the Pinpoint went nuts. I then re calibrated both monitors with Milwaukee 10.01 and 7.01. The pinpoint still read high..8.5 8.6 and the Milwaukee read the same 7.6. I think both meters are reading wrong, now my question is that even though they I was able calibrate both correctly, can the probe still be bad? I have read your article on PH monitors and solutions...

patrick

[Randy Holmes-Farley]

pH meters sometime go whacko when exposed to electrical/rf interference from aquarium lights, so if you get weird readings, try moving the sample away from the tank, and put it on the battery.


I would calibrate both together in the same fluids. If they read those fluids correctly after calibration (be sure to check that), I'd be surprised if there is much difference between them when reading a third sample together. There can be things that might make one slightly off from the other, but the differences should not be large.

[pk1]

I did try that (i think), after calibrating both meters using the same bags of fluid, the Milwaukee read fresh mixed aerated saltwater at 7.6 (always read 8.2 before), can't remember what the Pinpoint read that at though. I actually calibrated the probes twice using the same bag of fluid...(MIL 7.01 then to 10.01 then back to 7.01 then to 10.01 again, then to tank--7.6)...tonight I will try the Mil. meter on a separate circuit and see if that changes anything, and I'll calibrate both again.

[Randy Holmes-Farley]

OK, good luck. I don't know of anything else to suggest. :)

[pk1]

probably buy a new probe (which is what i didn't want to hear which is probably why you didn't say it :) :D )

Does the probe you suggest in your article connect to my meters? And if so, does it have a longer life than the Pinpoint or Milwaukee brand?

[Randy Holmes-Farley]

As long as the cords will actually connect (that is, they have a BNC connector) probes of different brands should work OK. Before buying a new one, you might soak the ones you have in acid overnight (to clean it; straight vinengar or muriatic acid diluted 10:1 with tap water) and then tap water for an hour or so (to rinse out acid), and then calibrate again.

[pk1]

I'll try soaking them first, thanks again for the quick and always kind responses.

patrick

[Randy Holmes-Farley]

:thumbsup:

Let us know what happens. :)

[pk1]

Well I cleaned both probes and re calibrated them both. The Milwaukee is fine, is now reading back to where it was before it went on the fritz, but the pinpoint has to be shot. It calibrated, and was reading the tank the same as the Milwaukee--but 4 hours later it was reading 6.65 PH! So thanks for the cleaning recommendation, you just saved me some cash $$$!

[Randy Holmes-Farley]

:thumbsup:

You're welcome.

Happy Reefing. :)