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General Category => Equipment and Software => Topic started by: blatz on July 08, 2011, 03:56:34 PM

Title: pH meter - what else is needed?
Post by: blatz on July 08, 2011, 03:56:34 PM
My wife is getting me a Milwaukee MW101 meter for my birthday coming up.  But I can't tell what comes with it and what other solutions I should get along with it.

She is buying through amazon since its pretty cheap - any advice would be helpful.

Tx
Title: Re: pH meter - what else is needed?
Post by: tygo on July 08, 2011, 03:59:29 PM
You'll need the two calibration solutions (4.0 and 7.0 buffers) and storage solution.  Other than that you should be good to go.
Title: Re: pH meter - what else is needed?
Post by: SpanishCastleAle on July 08, 2011, 04:00:04 PM
You'll need two calibration solutions, 4.01 and 7.01 and also some storage solution.  You can make your own storage solution with KCl and the 4.01 buffer but I just bought the premade solution.  There is also a cleaning solution but I didn't get any of that.

edit: sniped by tygo! :)
Title: Re: pH meter - what else is needed?
Post by: bluesman on July 08, 2011, 04:57:02 PM
Paul...I have the same meter and love it. It should come with 4 and 7 solutions. I use the White Labs vials for storing the probe and the solutions. I keep the soulutions in my cellar for cool storage. The meter is really easy to use and pretty darn accurate IMO. I store the probe in "tap water" as per the manufacturers recommendation (don't use distilled water for storage).

I take a small sample of the mash and quickly chill it down to RT. The meter responds very quickly. I get a steady reading within 10 seconds. I use distilled water and salts to build my water profiles then add the grain and wait 10 min before I take a reading. This instrument is probably one of the most valuable tools in my brewery.

Title: Re: pH meter - what else is needed?
Post by: tom on July 08, 2011, 06:40:55 PM
They now recommend storing it in "storage solution".

MW101 Manual: "After completing measurements, switch the meter off and store the electrode with a few drops of storage solution (MA9015) in the protective cap."
Title: Re: pH meter - what else is needed?
Post by: bluesman on July 08, 2011, 06:48:58 PM
They now recommend storing it in "storage solution".

MW101 Manual: "After completing measurements, switch the meter off and store the electrode with a few drops of storage solution (MA9015) in the protective cap."

That must have just changed.

I spoke to a Milwaukee rep about a month or two ago and his recommendation was "tap water".
Title: Re: pH meter - what else is needed?
Post by: zorch on July 08, 2011, 07:40:54 PM
They now recommend storing it in "storage solution".

MW101 Manual: "After completing measurements, switch the meter off and store the electrode with a few drops of storage solution (MA9015) in the protective cap."

That must have just changed.

I spoke to a Milwaukee rep about a month or two ago and his recommendation was "tap water".

I have this pH meter, and the package I bought came with a bottle of storage solution and a silicone protective cap that holds a bit of solution in contact with the probe.   So, certainly use that stuff if you have it.

Otherwise, tap water is better than distilled.


You'll probably want to get some additional calibration solution (4.01 and 7.01).  You can get it by the bottle, or you can get it in the little 20ml foil sachets.  I prefer the sachets because they are dead simple to use:  Just cut off the top and dunk the probe straight in.   
Title: Re: pH meter - what else is needed?
Post by: hubie on July 08, 2011, 07:47:58 PM
What is the shelf life for the reference solutions once opened, and how often to people calibrate?  My LHBS sells the sachets as well as bottles of the solutions.  I like the idea of the sachets, and I think you can order them in bulk, but I presume they are meant for single use.  I can see the attraction in getting the bottles of the solution, but only if they don't go bad after a short amount of time.
Title: Re: pH meter - what else is needed?
Post by: tom on July 08, 2011, 07:58:32 PM
My bottles usually have a "best by" date over a year from the purchase date.
Title: Re: pH meter - what else is needed?
Post by: blatz on July 08, 2011, 08:59:38 PM
cool - they had a package deal (4.01+7.01+storage) on sale, so that's what I told her to get - thanks fellas.

Title: Re: pH meter - what else is needed?
Post by: millstone on July 08, 2011, 11:34:57 PM
blatz, please post the Amazon link...

thanks

tom

edited for spelling
Title: Re: pH meter - what else is needed?
Post by: blatz on July 08, 2011, 11:57:25 PM
http://www.amazon.com/pH-Meter-Point-Manual-Calibration/dp/B0009YH06Y/ref=sr_1_1?ie=UTF8&s=home-garden&qid=1310169415&sr=8-1

Title: Re: pH meter - what else is needed?
Post by: euge on July 09, 2011, 01:03:57 AM
I store mine in the green General Hydroponics 7.01 calibration fluid. It also says "storage solution" on the label. Was emphatically advised not to use distilled or tap water to store the meter probe in.

I use the meter often and don't need to calibrate it very much.
Title: Re: pH meter - what else is needed?
Post by: tygo on July 09, 2011, 02:42:21 AM
I've found that the calibration holds pretty steady over time.  I used to calibrate before each use but since it doesn't seem to drift I only do it occasionally now.
Title: Re: pH meter - what else is needed?
Post by: denny on July 09, 2011, 04:25:15 PM
What is the shelf life for the reference solutions once opened, and how often to people calibrate? 

I calibrate every time I use my meter.
Title: Re: pH meter - what else is needed?
Post by: mabrungard on July 10, 2011, 03:46:00 PM
I find that now that I store my probe in storage solution, the calibration settings change very little.  This suggests that if you store the probe properly, the meter should maintain its calibration better.  I still check my calibration every session since its providing important information for my mash acidity vs pH calibration data set.  

Another consideration is that as the probe ages, its susceptability to calibration drift is greater.  I would check the calibration every several sessions in any case.
Title: Re: pH meter - what else is needed?
Post by: Thirsty_Monk on July 11, 2011, 02:43:03 AM
Can you buy a replacement probe for this pH meter?
Title: Re: pH meter - what else is needed?
Post by: narcout on July 14, 2011, 01:46:00 AM
Can you buy a replacement probe for this pH meter?

Yes.
Title: Re: pH meter - what else is needed?
Post by: Thirsty_Monk on July 16, 2011, 02:55:01 PM
Cool, I have 10 more test strips. I am due to get me a pH meter :)
Title: Re: pH meter - what else is needed?
Post by: blatz on August 07, 2011, 03:29:40 AM
little confused here - I brewed a fest yesterday - pH read 5.61 at room temp and 5.44 at mash temp.  I know its a little high, but I think I'm okay - gravity etc was fine.  More important, does that differential seem right?  I thought it should be 0.3 difference between mash and room temp readings?

Title: Re: pH meter - what else is needed?
Post by: blatz on August 08, 2011, 03:40:35 PM
also - is there a good reason why I couldn't save some of the calibration solutions (in white labs tubes) for future use? 

Title: Re: pH meter - what else is needed?
Post by: bluesman on August 08, 2011, 04:02:23 PM
little confused here - I brewed a fest yesterday - pH read 5.61 at room temp and 5.44 at mash temp.  I know its a little high, but I think I'm okay - gravity etc was fine.  More important, does that differential seem right?  I thought it should be 0.3 difference between mash and room temp readings?



I wouldn't worry too much about that difference, although I would be curious as to why it varied at that rate. You're within range, so you should be fine with it either way. I assume you calibrated your meter prior to taking your readings?
Title: Re: pH meter - what else is needed?
Post by: mabrungard on August 08, 2011, 04:31:55 PM
I thought it should be 0.3 difference between mash and room temp readings?

There is disagreement as to the difference in pH between mash and room temperature measurements.  For instance, Malting and Brewing Science states that the difference is about 0.35 units.  You and other sources quote a 0.3 unit difference.  Measurements by AJ Delange and Kai Troester indicate its more like 0.2 units. 
Title: Re: pH meter - what else is needed?
Post by: gordonstrong on August 09, 2011, 06:42:09 PM
I measured it for my book using lab-grade equipment; it was about 0.3 to 0.35.  But I was measuring distilled water, not mash.  I think AJ was suggesting that it might be less of a difference that way.  I'd like to try some experiments with different liquids and see if it makes a difference.

If you're talking about a 0.05 difference, you also have to look at the precision of your instrument.  Can it resolve to that level?  How is it rated?

Also, you say "mash temps".  It's a curve, so the difference isn't the same across all mash temperatures.  I'd have to go back to check my data to see where it was 0.3 and where it was 0.35, but it was likely in single infusion ranges.

A 0.05 difference in pH isn't going to affect your beer in any meaningful way, so I don't know that it's worth arguing about.
Title: Re: pH meter - what else is needed?
Post by: blatz on August 09, 2011, 07:02:38 PM
I use the MW 101  http://www.water-testers.com/contents/en-us/p4324_milwaukee_mw101_ph_meter.html

like you said, the more I think about, the less it is worth worrying about.

One thing that was cool - Martin's sheet said the pH at room temp should come out to 5.6, and it did.  Too bad, I forgot to go back and change my salt additions when I rearranged my grist - I would have shot for 5.4-5.5 instead, but all should be good.
Title: Re: pH meter - what else is needed?
Post by: hubie on August 10, 2011, 02:05:05 AM
I think the temperature dependence depends upon how acidic the solution is, and if that is true (and my subconscious isn't telling me that just to mess around with me), then it should depend upon the mash composition: mashes with highly kilned malts should act different than distilled water.  Of course the chemistry in a mash involves many different compounds with different dissociation rates, some that increase the pH and some that decrease the pH, so the real answer is probably not so neat.

This is why I went into physics.  I much prefer to break the problem down into a simple idealized system:  let's assume a spherical mash tun...
Title: Re: pH meter - what else is needed?
Post by: mabrungard on August 10, 2011, 12:49:22 PM
I think the temperature dependence depends upon how acidic the solution is

This factor might have some relevance.  I had not thought about it prior.  But, it may not really be that significant since we focus on a relatively narrow pH range for mashing since it tends to optimize our mashing performance.  For those cases where the brewer does not manage their mash pH, then I concur that the acidity and temperature dependence could affect the typical pH offset that has been reported.
 
Title: Re: pH meter - what else is needed?
Post by: narcout on August 10, 2011, 06:35:01 PM
little confused here - I brewed a fest yesterday - pH read 5.61 at room temp and 5.44 at mash temp.  I know its a little high, but I think I'm okay - gravity etc was fine.  More important, does that differential seem right?  I thought it should be 0.3 difference between mash and room temp readings?

How did you measure the pH at mash temperature?  I have the same meter as you and the maximum temperature compensation is 50 degrees Celsius (122 degrees Fahrenheit).

I've also heard that it isn't good for the probe to immerse it in mash temperature liquids. 
Title: Re: pH meter - what else is needed?
Post by: blatz on August 10, 2011, 06:42:33 PM
little confused here - I brewed a fest yesterday - pH read 5.61 at room temp and 5.44 at mash temp.  I know its a little high, but I think I'm okay - gravity etc was fine.  More important, does that differential seem right?  I thought it should be 0.3 difference between mash and room temp readings?

How did you measure the pH at mash temperature?  I have the same meter as you and the maximum temperature compensation is 50 degrees Celsius (122 degrees Fahrenheit).

I've also heard that it isn't good for the probe to immerse it in mash temperature liquids. 

154.  yes, I know its bad, but I couldn't help myself.  :-[
Title: Re: pH meter - what else is needed?
Post by: gordonstrong on August 10, 2011, 06:50:31 PM
I was using gear in a chemistry lab that was rated for those temperatures.  I wouldn't do it on consumer gear that isn't rated for it.
Title: Re: pH meter - what else is needed?
Post by: Thirsty_Monk on August 11, 2011, 03:22:47 AM
154.  yes, I know its bad, but I couldn't help myself.  :-[
I see. Still no step mashing!!!
Title: Re: pH meter - what else is needed?
Post by: blatz on August 11, 2011, 12:45:55 PM
154.  yes, I know its bad, but I couldn't help myself.  :-[
I see. Still no step mashing!!!

once the brewery (and the house around it are finished) I promise to try it - it will be much easier to step mash being electric and HERMS  ;)