pH Meter Calibration points?

[robert81650]

Hey this pH thing you guys are fretting about is not a rocket shot to the moon. After all this is home wine making and what we get as far as a pH reading on a good meter should be adequate as long as the wine tastes good and is stable for storage for several years to age.

 

[runswithsizzers]

Hey this pH thing you guys are fretting about is not a rocket shot to the moon. After all this is home wine making and what we get as far as a pH reading on a good meter should be adequate as long as the wine tastes good and is stable for storage for several years to age.

Maybe some people are born knowing the definition of "a good pH meter" and how to use one, but I wasn't. Sorry to bother you.

 

[Boatboy24]

I normally do a two point check since that what my Milwaukee (MW 101) meter suggests. Additionally you may want to think about getting another solution (https://www.piwine.com/ph-3-buffer-solution-4-oz.html) with a pH of 3.0. I use it after calibration to double check that nothing went too far awry with my two point calibration. If it reads too high or low, I adjust my readings slightly either way (depending on the pH) or better yet, perform the calibration again until my readings on the 3.0 solution are closer.

Craig: How do you store the probe? My initial meter purchase was a pHep 5, which is supposed to be a decent meter (about $85 at the time). It would never settle on a reading. I've since gone through a couple cheap (sub $20) meters. They calibrate perfectly for a bit, but eventually conk out after a year, maybe less. I want something reliable, but I'm starting to feel like storage is key. I've been using the 'pen' style meters with storage solution in the lid. What do you use, how often do you calibrate/use your meter, and what is your process. I'm thinking of a MW meter, but don't want to spend the $$ if it is going to crap out on me after a year.

 

[ceeaton]

Craig: How do you store the probe? My initial meter purchase was a pHep 5, which is supposed to be a decent meter (about $85 at the time). It would never settle on a reading. I've since gone through a couple cheap (sub $20) meters. They calibrate perfectly for a bit, but eventually conk out after a year, maybe less. I want something reliable, but I'm starting to feel like storage is key. I've been using the 'pen' style meters with storage solution in the lid. What do you use, how often do you calibrate/use your meter, and what is your process. I'm thinking of a MW meter, but don't want to spend the $$ if it is going to crap out on me after a year.

The MW 101 series has a tube with a rubber seal that seems to keep the storage solution from evaporating and leaving a salt like residue behind. I think when the membrane part of the probe dries out it may plug with whatever residue is in the solution you store it with, then needs a cleaning to get rid of it. If you can keep it from drying out or the solution concentrating, I think that's half of the battle. Mine is stored in the cool basement, but I bring it and my solutions up the day before I test (unless it's summer, where the temps between the basement and upstairs are rarely more than 10*F difference) so thanks for the reminder, I'm hoping to get some wine "stuff" done tomorrow while it is raining. I've only had mine a couple of years, but I think the nice thing is the probe is a stand alone item you can buy if it goes south on you. Mine was just over $100 shipped. You can get them cheaper, but I bought mine because it didn't have the temperature correction function, and I think that is what went haywire on my Hanna meter, especially if the temperature wasn't stable (ie. I forget to bring it upstairs that night before testing). Hope that helps. You are more than welcome to try mine out, but I don't have a car this weekend (18 yr old daughter hijacked it) so you'll have to drive up here!

 

[rsportsman]

I recently bought my first pH meter - a Hanna Checker, Model HI98103 <details here> Mine is the newer model, and accuracy is +/- 0.2 pH. I am using it for both juice/must/wine and TA (total acid) titrations.

My model is capable of either one-point or two-point calibration. Hanna provides calibration material at pH 4.01, 7.01, and 10.01, and I believe the meter calibration process relies on using one (or two) of these levels. If doing a two-point calibration, one of the levels must be 7.01.

In <this thread> ibglowin says
"[Use] Only the 4.0 since the wines pH is always between 3.2 - 3.9. If you use 4.0 and 7.0 your basically calibrated then between those values. Your better off with a single point 4.0 since your samples is usually so close to the 4.0 anyway."
... to which grapeman replied,
"Unless you use your meter for doing a TA test where you go to 8.2 and then you need to calibrate using both."

Following that advice would require calibrating my pH meter at 4.0 for wine and juice (one point), and at 7.01/10.01 (two-point) for TA titrations, right? While that is doable, it also would require a lot more time and materials to recalibrate every time I switch from wine to a TA titration. Which I would prefer to avoid unless necessary.

Does anyone know just how much accuracy suffers at pH 3.2, and at pH 8.2 - if my meter is calibrated from 4.0 to 7.0?

Maybe it would be best to have two pH meters, one calibrated for juice/wine and one for TA titrations? They are cheap enough. If I get another one, I might consider <this one> which has no better accuracy than my Checker, but is made to be more reliable for juice/wine because it protects the probe better from particles. And it comes with pH 3.0 and 7.0 calibrators.

On the other hand, maybe it makes more sense to own one good pH meter, which can hopefully store two calibration curves, rather than two cheap meters? Like <this one>?

A good trick is to use cream of tartar, AKA potassium hydrogen tartrate (KHT), to check your accuracy of calibration. Add 1/8 tsp cream of tartar (grocery store stuff is fine as long as it's pure) to 20 mL distilled water and mix well for about 30 seconds. This provides a "saturated solution" of KHT. A properly calibrated pH meter should read this solution as pH 3.56 at 25C. (doesn't change much with +/- 5C). I am usually OK with a reading between 3.50 and 3.60. Discard this solution after 24 hours. - Rich from Vinmetrica

 

[runswithsizzers]

I have since replaced the Hanna Checker mentioned in my original post with a ThermoWorks pH meter, # 8689. The ThermoWorks meter is more accurate than the Hanna (+/- 0.05 vs. +/- 0.2 pH), and the ThermoWorks also allows for 3-point calibration. I paid $80 (US) for the ThermoWorks #8689 (on sale) compared to $58 for the Hanna at my semi-local brew store. <link here>

The calibration instructions for the 8689 were not entirely clear, so I called for ThermoWorks clarification. I was amazed when a real person answered the phone and he answered my questions in good English!