pH Meter Question - Is mine dead or not

[DonnieZ]

Last year in June I did some brewery upgrades, and a pH meter was one of them.

I purchased the HM PH-200 meter from Amazon.

My first couple of brews I used it and it read in line with what I was expecting for Mash pH.

However, life got busy and I didn't get back to brewing until late October. Brought out the pH meter and my pH readings always seemed high even though my water adjustments predicted them to be in the 5.4 range. The meter has been reading in the 5.8-6.2 range for the last few brews.

What really questioned my trust in the meter is that I brewed my house IPA for the first brew, and I got a dead nuts on 5.4 pH as predicted by Brun' Water with my water adjustments and the grain bill. I brewed the same recipe using the same water adjustments in October and got a 5.8 pH reading. I brewed it again on New Years Day and got a reading in the 5.9-6 range.

I took it over to a buddy's house yesterday for a collaboration brew and his meter read about .5 lower than mine did on the same sample at the same temp.

I think this does point to the pH meter being a little off. I understand the concept of pH, however I'm a little sketchy on exactly how pH meters work and why this might be happening.

For the record, I take my wort samples from the mash about 5-10 minutes into the mash in a clean, small taster glass. I chill down to about 77 degrees and then take the sample with the meter. Prior to each sample, I've been calibrating the meter with 4.0 buffer solution also in a clean taster glass. I've been storing the electrode in a small amount of 4.0 buffer solution in the cap.

Are these things really that sensitive, did I just get a bum unit, or is it possible I'm just doing something wrong with the probe or the sample?

 

[GotPushrods]

It sounds like you are calibrating before each brew session which is good. Are you doing a 2-point calibration with 4 and 7? You need both or your meter doesn't have enough information to draw a calibration line.

Are you pouring buffer out of the bottle into a separate test jar, and discarding after calibration? The buffers can become contaminated. Use your buddies pH meter and check your buffers.

I've been using the Hach buffer pillows for some time now and will never go back to liquid. I was always paranoid as to the integrity of my aging bottles of buffer.

 

[DonnieZ]

Interesting. I thought it just had to be calibrated at 4 or 7, not both.

I pour the buffer out into a clean glass container (Usually a shot glass, or a clean taster glass from one of the many beer festivals I've attended). Yes, I do discard the buffer solution after testing. I will check the buffers and see how it goes. I've got liquid buffers from some hydroponic supply. I'm sure they're some generic buffer solution that they get in bulk and rebrand. (Link)


Ok. I will try that and see how it goes next time. Maybe that's been the issue I've been having.

 

[Spartan1979]

Are you calibrating your meter before each brew day? In both 4 and 7? If not, you need to. Is your buddy calibrating his meter each day? If not, a comparison to his meter isn't worth much.

pH buffer solution probably is not the correct thing to be storing your meter in. There are solutions that are designed to be used for that purpose.