Anomalies with Mash pH Measurements

[specharka]

Hey guys, I wasn’t sure what subforum to put this in, so I’m sticking it here.

I’ve recently been having a lot of problems with my Apera PH60 meter. I performed the required 2-step calibration procedure, but my measured pH is ALWAYS off — from the calibration solution or my calculated mash pH, and by a significant margin (0.3 pH units).

Today I’m brewing an amber lager, here’s the recipe:

OG 1.055, FG 1.015, IBU 24, SRM 7

39% Vienna
30% Munich I
15% Pilsner
15% Munich II
1% Acidulated

Water built from RO source to amber balanced profile in B’runWater. 0.3 g/gal CaSO4, 0.35 g/gal CaCl, 0.3 MgSO4 added to mash water. Mash sampled @ 15 minutes into saccharification rest.

The Hanna Instruments pH meter has not been recently calibrated, but it’s still much closer to what I was expecting (calculated 5.45 pH). So what gives?
Are my calibration solutions bad?
Do I need to get a new electrode for my meter?
Are my water calculations erroneous?

 

[SoCal-Doug]

Are my calibration solutions bad?

Possibly. Never re-use calibration solution. Pour what you need to calibrate, then discard. Keep the containers closed when not in use.

Do I need to get a new electrode for my meter?

Possibly. After calibrating both meters, test a calibration solution and some other solution with both meters. see if they give you the correct and similar result. Try a 3rd meter and see who is consistently the "odd man out"

Are my water calculations erroneous?

Possibly. But bru-n-water is pretty much dead on (within .1 or .2 in my experience) as long as you give it the correct data

Other thoughts:
* Always rinse the probe with distilled water before and after use.
* Even if the meter has temp correction, very hot and very cold should be avoided
* Always store probes in a quality storage solution. Probe's are soft and almost gel like, if they dry out, they will not work correctly.
* Make sure there is no damage to, or schmutz stuck on the probe.

 

[Desert_Sky]

Never reuse the cal liquid. You can get pretty big bottles of ph4 and ph7 off amazon for pretty cheap.

If electrode dries out, its best to replace it. i keep the lid full of water before I cap and store

 

[specharka]

Possibly. Never re-use calibration solution. Pour what you need to calibrate, then discard. Keep the containers closed when not in use.


Possibly. After calibrating both meters, test a calibration solution and some other solution with both meters. see if they give you the correct and similar result. Try a 3rd meter and see who is consistently the "odd man out"


Possibly. But bru-n-water is pretty much dead on (within .1 or .2 in my experience) as long as you give it the correct data

Other thoughts:
* Always rinse the probe with distilled water before and after use.
* Even if the meter has temp correction, very hot and very cold should be avoided
* Always store probes in a quality storage solution. Probe's are soft and almost gel like, if they dry out, they will not work correctly.
* Make sure there is no damage to, or schmutz stuck on the probe.

Hmm...the instructions only specify rinsing with tap water and drying the probe before each measurement. Aside from that, I was already aware of the other stuff.

I’m definitely gonna order more calibration and storage solutions. Mine are easily 12-18 months old. I was trying to avoid buying a new electrode ($$$), but if it’s one less room for error, I guess I can.