Looking for PH Meter Suggestions

[ajdelange]

The buffers are at the labeled pH values only at 25°C. At other temperatures their pH's are slightly different. There should be a chart on the buffer package that tells you what the pH is at various temperatures. If you calibrate and then measure at 25° C you should get pretty darn close to what the buffer was labeled as long as your reading is between (or equal to) the buffers used for the calibration. IOW calibrating with 4 and 7 buffer should get you what the buffer label says if you go back and measure 4 and 7 buffer. But you can't expect that with 10 buffer and a 4 &* 7 cal,

 

[Bigscience]

Got the Hanna pHep 5 yesterday. Bulb was dry. Brought it to work to calibrate it (we have buffer solutions 2, 4, 7, 8, 10, and 12). I put it in 7 buffer solution and left it there for ~4 hours (per mfr instructions). I first cal'd it with 7 and 4 buffer solutions and after cal it would read those solutions as 7.02 and 4.03 respectively. Tried again, same result. Then I stuck it in 10 buffer and it read 10.05. So I tried cal'ing it with 7 and 10 and that got 4.01 and 7.01 but still read the 10 buffer as 10.04.

Is this reasonable or should it be dead nuts in each solution? I'm sure it's close enough for shade-tree brew geekery but should it be closer?

FWIW RonRock, this Hanna meter can switch between C and F.

I'm not sure what cal solutions you got but they are normally 7.01 and 4.01 not 7.00/4.00. Since the accuracy of this model is +/- 0.05, I think you are good.

So would you buy this one again or do you think it's a POS?

 

[SpanishCastleAle]

I'm not sure what cal solutions you got but they are normally 7.01 and 4.01 not 7.00/4.00. Since the accuracy of this model is +/- 0.05, I think you are good.

So would you buy this one again or do you think it's a POS?

The solutions I used were from Fischer Scientific, called 4.00 and 7.00, and the labels said 3.99-4.01 @ 25* C and 6.99-7.01 @ 25* C.

I've only measured some finished beers and first used it for a brewday just this past weekend. I have no baseline but it seemed to work fine and was easy enough to use. I did have one little issue: by the time I collected/chilled/measured the sample it had already been 15-20 minutes into the mash and that seemed a little late to be adjusting it (it was 5.62). So I added a little lactic acid to the sparge water and the pre-boil pH was 5.55, post-boil was 5.40. It was a Russian Imp Stout with 50% distilled water + a tiny bit of CaCl.

 

[ajdelange]

This is normal. "Technical" buffers usually are specified to ± 0.02 pH. It seems you bought buffers specified to ±0.01.

The NIST technical buffer for pH 4 has nominal pH 4.00762 (4.01) at 25°C and the 7 buffer pH 6.99992 (7.00) at the same temperature.

 

[SpanishCastleAle]

This is normal. "Technical" buffers usually are specified to ± 0.02 pH. It seems you bought buffers specified to ±0.01.

The NIST technical buffer for pH 4 has nominal pH 4.00762 (4.01) at 25°C and the 7 buffer pH 6.99992 (7.00) at the same temperature.

The buffers I'm using are buffers we have at work (half of my building is a Chemical Anaysis lab), so that may be why they are so tight.

 

[RonRock]

Now that Christmas is past I'm ready to pull the trigger. Any other suggestions before I buy an MW-102? I'm still not sure if the lack of Fahrenheit temp reading is going to bother me.

 

[RonRock]

No more input from anyone on this?

 

[Randar]

I have the cheap Checker pH meter and so far I like it. Simple and easy and a couple of decimal points too boot.

http://www.amazon.com/dp/B000WTELF4/?tag=skimlinks_replacement-20

I spent 25 bucks on cleaning and storage solutions as well.

 

[sudsmcgee]

So, dumb question. How do you store the probe in storage solution? Do you remove it from the meter after each use? Or put the solution in the cap?

I have a Hannah HI 98127.

 

[ajdelange]

The latter.

 

[Bigscience]

Store it upright too so you don't get crusties forming around the cap.

 

[SpanishCastleAle]

Store it upright too so you don't get crusties forming around the cap.

I do store mine upright and still get the crusties.

 

[sudsmcgee]

Thanks!

 

[ajdelange]

Saturated potassium chloride solution is interesting stuff. It can climb out of beakers (so that they empty at a rate several times that explainable by evaporation) and work its way through closures which are otherwise liquid tight. It is therefore important that you check that your meter cap contains some liquid from time to time if the meter is stored for long periods.