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General Category => General Homebrew Discussion => Topic started by: lonetreedavid on February 10, 2010, 06:07:22 AM

Title: pH Meters
Post by: lonetreedavid on February 10, 2010, 06:07:22 AM
There was a discussion a few months ago about storing (and calibrating) pH meters.
However, I'd really like recommendations about particular models - especially the Hanna Instruments Beer Testing models.
Any opinions??
thanks
Title: Re: pH Meters
Post by: euge on February 11, 2010, 05:46:40 PM
Well you want to use the General Hydroponics 7.0 pH calibration fluid for storage.

I haven't owned a Hanna but bought an Ecotester instead. It is waterproof, accurate and only cost me about $75 at the LHS.

Example:

http://www.pulseinstruments.net/index.asp?PageAction=VIEWPROD&ProdID=2884 (http://www.pulseinstruments.net/index.asp?PageAction=VIEWPROD&ProdID=2884)

AFAIK the Hanna's are a popular brand. Costly.
Title: Re: pH Meters
Post by: Kaiser on February 11, 2010, 11:11:03 PM
Is that a pH meter designed for beer? Do you have a model Name/number?

Kai
Title: Re: pH Meters
Post by: lonetreedavid on February 12, 2010, 07:29:36 AM
This is the link from the Hanna website for Beer pH testers

http://www.hannainst.com/usa/prods2.cfm?id=031003

let me know what you think
Title: Re: pH Meters
Post by: euge on February 12, 2010, 05:02:16 PM
I don't see why not. I've used it for testing my mash, water etc. As long as I keep it calibrated.
Title: Re: pH Meters
Post by: mrcceo on February 13, 2010, 01:42:14 AM
I can probably help you.  I started with the Hanna 98103 but didn't have much faith in it.  I subsequently purchased a lab quality meter.  I'll run a side by side test tomorrow and post the results for you.
Title: Re: pH Meters
Post by: Kaiser on February 13, 2010, 04:43:21 AM
How much are those simple Hanna meters? If the precision is only 0.1 - 0.2 units you may be better of using colorpHast strips.

Kai
Title: Re: pH Meters
Post by: euge on February 13, 2010, 06:31:17 AM
Kai I apologize I didn't read your post fully.

It's an Ecotester pH1 I think it has Oakton guts... whatever that means.

http://www.hydroponicsoutlet.com/Oakton-Meters-Waterproof-EcoTster-pH1-p/ok35423-00.htm (http://www.hydroponicsoutlet.com/Oakton-Meters-Waterproof-EcoTster-pH1-p/ok35423-00.htm)
                               
http://www.eutechinst.com/pdt-para-ph-ecotestrph1.html (http://www.eutechinst.com/pdt-para-ph-ecotestrph1.html)
Title: Re: pH Meters
Post by: Kaiser on February 13, 2010, 01:17:50 PM
For that price you can also get one that has 0.02 pH accuracy. Although it wouldn't have ATC and automatic calibration. But I think that those features are not necessary. Here is something I wrote about selecting a pH meter for brewing: http://braukaiser.com/wiki/index.php?title=PH_Meter_Buying_Guide

Kai
Title: Re: pH Meters
Post by: lonetreedavid on February 13, 2010, 05:18:26 PM
Thanks for the link to your article, Kaiser.
Do you have other articles that you could please send me links to?

but what's the bottom line on pH meters?
I want a recommendations for a good meter in the $50 range
Title: Re: pH Meters
Post by: tom on February 13, 2010, 06:58:36 PM
I have had 2 of these: http://www.hannainst.com/usa/prods2.cfm?id=031003&ProdCode=HI 98128  although it was 0.01 accuracy when I got it. The first lasted several years. The second only lasted 1-2 years, but I didn't store it in the storage solution.
Now I have a Milwaukee.
Get the calibrating solution in 16 oz bottles from your local science supply store.
Title: Re: pH Meters
Post by: mrcceo on February 14, 2010, 12:30:25 AM
The results of the test between the bench top meter (Radiometer PH 220) and the Hanna meter 98103 summarizes as follows:
Six samples were tested ranging from a PH of 6.94 to 2.70
Prior to running the test both meter probes were stored wet, in an approved storage solution.
The probes were hydrated/rinsed for 30 minutes; then were calibrated using standard buffer solutions of 4.01 and 7.01. Both meters held stable readings during calibration.
All samples were tested at 21 degrees Celsius and the probes were rinsed between tests and blotted dry.

The bench top meter was able to reach a stable reading within 32 seconds on average. The pocket meter could only obtain a stable reading on lower PH solutions and would often drift for 10 minutes, which was the cut off point for the test s. The difference between the readings of the two meters ranged on average .32 

It should be noted that the drifting of the reading is what initially frustrated me about the Hanna meter.  Although the drift eventually slowed to the point that I was willing to accept the reading I never trusted it and went back to PH test strips before getting the bench top meter. 

Based on my experience I would suggest staying away from the lower priced meters in favor of PH test strips.  If you are going to invest in a meter start by visiting Kai’s website.  He has some very good information on Ph and the meter he’s using.

Hope this was helpful
Title: Re: pH Meters
Post by: Kaiser on February 14, 2010, 01:19:33 PM
mrcceo,

Thanks for sharing the test results. I assume that during the test the samples were stirred or the probes were agitated. I tend to see drifts too, but only when I don't move the probe. Also, were the samples well buffered? I think the lab grade pH meter really shine when the sample's pH is very weakly buffered. Soft water is a good example. But most solutions we test in brewing are strongly buffered.

David,
Keep in mind that the simple Hanna meters are advertised as replacements for strips. They seem to have a comparable accuracy. Given the precision with which we want to hit the mash pH, 5.3 - 5.6 is good, they should be acceptable. But if you are technically inclined you may look for more accuracy in the future. It is my opinion that a good simple pH meter with buffers and storage solution can be had for under $100. That is the SM101 that I mention in the article.

Kai
Title: Re: pH Meters
Post by: mrcceo on February 14, 2010, 10:10:09 PM
Kai:
I did agitate the solutions but did not buffer them.  I based the testing procedures on the instructions that came with the Hanna meter since that meter's performance was in question. 
Title: Re: pH Meters
Post by: denny on February 15, 2010, 09:08:03 PM
I just posted some similar questions in the equipment section, but I'll repeat them here....I'm looking at a Milwaukee pH51 at the LHBS.  According to Kai's buyers guide, I should be looking for an accuracy of .01ish.  If I read this correctly (http://www.milwaukeetesters.com/pdf/pH51.pdf), the pH 51 is only .1?  All I'm really interested in is mash pH, and Kai's writeup implies that might be OK for that that purpose.  Anybody used this model?
Title: Re: pH Meters
Post by: denny on February 15, 2010, 09:11:30 PM
I have had 2 of these: http://www.hannainst.com/usa/prods2.cfm?id=031003&ProdCode=HI 98128  although it was 0.01 accuracy when I got it. The first lasted several years. The second only lasted 1-2 years, but I didn't store it in the storage solution.
Now I have a Milwaukee.
Get the calibrating solution in 16 oz bottles from your local science supply store.

What model of Milwaukee, Tom?
Title: Re: pH Meters
Post by: tom on February 16, 2010, 12:05:19 AM
SM 102. It has a separate temperature probe and automatic calibration.

Kai likes the SM 101 because it has manual calibration. I think he had a previous meter that stopped automatically calibrating. But it doesn't have a temperature probe.

I like the temperature probe to make sure I'm not putting the pH probe in wort that's too hot. Of course you can get your own separate thermometer! And you probably already have one of those.

Brew on!
Title: Re: pH Meters
Post by: denny on February 16, 2010, 05:04:13 PM
Well, I think I'm gonna pull the trigger on the pH51.  May not be the best meter out there, but it looks like it will fulfill my needs....and besides, my BIL is paying for it!  :)
Title: Re: pH Meters
Post by: euge on February 16, 2010, 05:58:30 PM
I just posted some similar questions in the equipment section, but I'll repeat them here....I'm looking at a Milwaukee pH51 at the LHBS.  According to Kai's buyers guide, I should be looking for an accuracy of .01ish.  If I read this correctly (http://www.milwaukeetesters.com/pdf/pH51.pdf), the pH 51 is only .1?  All I'm really interested in is mash pH, and Kai's writeup implies that might be OK for that that purpose.  Anybody used this model?

Denny, the resolution and variance for that model are both 0.1 pH. I don't really see where a resolution to a hundredth in homebrewing would help any more than a tenth. But, always nice to have.

That unit has a manual callibration screw and replaceable electrode. Nice!
Title: Re: pH Meters
Post by: Kaiser on February 16, 2010, 06:06:30 PM
Denny, the resolution and variance for that model are both 0.1 pH. I don't really see where a resolution to a hundredth in homebrewing would help any more than a tenth. But, always nice to have.
 

If you’re just looking to check mash pH and maybe also boil pH an accuracy of +/- 0.1 should be fine. If you have greater resolution you can also use it to check your beer pH and detect if you have problems with autolysis for example. That causes an unusually high rise in beer pH after fermentation. I never noticed anything dramatic but I thought of it when I opted for higher precision model. I also needed better precision to do the mash pH experiments I did.

Kai
Title: Re: pH Meters
Post by: denny on February 16, 2010, 06:09:20 PM
I can see why you'd prefer a higher res for the work you do, Kai, but I'm just looking for something better than the ColorpHast strips I've been using.  I think this will be OK for my purposes.  Thanks for your comments!
Title: Re: pH Meters
Post by: euge on February 16, 2010, 06:20:29 PM
Denny, the resolution and variance for that model are both 0.1 pH. I don't really see where a resolution to a hundredth in homebrewing would help any more than a tenth. But, always nice to have.
 

If you’re just looking to check mash pH and maybe also boil pH an accuracy of +/- 0.1 should be fine. If you have greater resolution you can also use it to check your beer pH and detect if you have problems with autolysis for example. That causes an unusually high rise in beer pH after fermentation. I never noticed anything dramatic but I thought of it when I opted for higher precision model. I also needed better precision to do the mash pH experiments I did.

Kai


Thanks Kai! I also have  been concerned with this. Didn't know about the pH upswing. I got a beer that sat on the yeast a little too long for my preferences. Taste test gives me "umami" and I'm worried. I don't have a reference but the pH will get checked anyway.

Denny, I had to get a meter since the pH strips I got from the LHBS were total crap. The resolution was 2. Yes 2! Not 0.2... extremely difficult to decide what the pH is and when the digital got used how off I was became very apparent. However the Colorphast has a "narrow range" http://www.sanitationtools.com/products.asp?category=72&attriberror=true&Product=1391 (http://www.sanitationtools.com/products.asp?category=72&attriberror=true&Product=1391) which should be better.
Title: Re: pH Meters
Post by: denny on February 16, 2010, 06:51:01 PM
However the Colorphast has a "narrow range" http://www.sanitationtools.com/products.asp?category=72&attriberror=true&Product=1391 (http://www.sanitationtools.com/products.asp?category=72&attriberror=true&Product=1391) which should be better.

Those are the ones I use, but I started wondering about them because it seems like my pH always shows up in range, even for a variety of beer colors.  I even ordered a new pack recently in case my older ones had gone bad.  Maybe I'm colorblind and just can't see the changes in them....
Title: Re: pH Meters
Post by: Tim McManus on March 21, 2011, 07:46:56 PM
Rather than start a new thread about pH meters, I thought I would resurrect this one since I found an earlier thread that referred to it.

I have some meter questions for the experienced and experts out there.

I recently picked up a Milwaukee ph56 from Cynmar and will be using it to test the pH of our darker beers.  Some of the questions I have are specific to this model, but the answers might be useful for other meters as well.

We brew anywhere from 1-4 batches a month of various styles.  Although the intent was to test the darker beers, I'll probably use them for all beers just because I can.  Do I need to calibrate the meter before each batch, or is it more of a once every x months sort of thing?

I understand that I need to store it in a 4.01 solution or bottled water to keep the probes wet.  The ph56 comes with cap over the probes.  Is this something that I should fill with the solution, or should I get a small beaker and leave the probe in there?  I am worried about evaporation and some klutz (me) knocking the solution over.  Does anyone have any suggestions on storage?  It came with a nice case, but if I have to store it wet, the case becomes kind of useless.  Also, when I transport it to the brewery, do I need to do it in the solution, or can I remove it from the solution for the 10-minute drive and subsequent 5-6 hour brew day?

Based on my brewing frequency noted above, should I buy bottles of calibration solution or packets?  Packets seem more convenient since I can grab a 4.01 and a 7.01 and be set for the day, but bottles are probably cheaper in the long run.  I am worried about spoilage since the solutions are dated.  Does the solution degrade with exposure or time?

Thanks in advance!
Title: Re: pH Meters
Post by: Kaiser on March 21, 2011, 09:07:56 PM

We brew anywhere from 1-4 batches a month of various styles.  Although the intent was to test the darker beers, I'll probably use them for all beers just because I can.  Do I need to calibrate the meter before each batch, or is it more of a once every x months sort of thing?
My experience has been that calibration is not necessary very often. I now do it maybe once a month or before a series of experiments and even then I find that it is only off by 0.01 – 0.02 units. Check the pH of the buffers once in a while to see how much drift you are actually getting.

Quote
I understand that I need to store it in a 4.01 solution or bottled water to keep the probes wet.  The ph56 comes with cap over the probes.  Is this something that I should fill with the solution, or should I get a small beaker and leave the probe in there?

To my knowledge pH meters should not be stored in their buffer solutions. They come with storage solution and you should buy an additional bottle. The storage solution is usually saturated potassium chloride (KCl), which is the same solution that’s inside the probe.

Keep some storage solution in the cap. Just enough that it doesn’t come out when you insert the probe. Also store the tester upright. I’m not sure what Milwaukee’s recommendations are but I’d make a stand that the tester can stand upright in.

Quote
Based on my brewing frequency noted above, should I buy bottles of calibration solution or packets?  Packets seem more convenient since I can grab a 4.01 and a 7.01 and be set for the day, but bottles are probably cheaper in the long run.  I am worried about spoilage since the solutions are dated.  Does the solution degrade with exposure or time?

I doubt the solutions expire. They are inorganic compounds. I have one 500 ml bottle of 4.00 and 7.00 calibration buffer each. I also have 4 oz bottles where I keep 2 oz of the buffer for calibration. Although this is not recommended I actually reuse the calibration buffers over the course of 6-8 months. They are so strong that their pH doesn’t drift more than 0.02 units during the time that I use them over and over again. But I also make sure that I rinse the probe with RO or DI water before I put it into any of the calibration buffers. Reusing pH buffer solution keeps me from having to buy new ones all the time.

Kai
Title: Re: pH Meters
Post by: mabrungard on March 21, 2011, 09:17:58 PM
You can create your own storage solution by dissolving potassium chloride into pH 4 buffer solution at a rate of 10 grams per 100 ml of liquid.  It takes a day or two to dissolve the KCl.  I've read that it is preferrable to use a slightly acidic solution.  The buffer solution supposedly also has mold inhibitors in it.

I used a White Labs vial which holds about 40 mL of liquid and I added 4 grams of KCl.  I drilled a hole in the cap of the vial to tightly fit my probe.  I then wrapped a wire around the vial and attached it to the peg board on my bench.  I always know where the meter is and its storage solution. 

Enjoy.
Title: Re: pH Meters
Post by: Tim McManus on March 21, 2011, 09:46:30 PM
Thanks, guys.

Too bad the ph56 doesn't have a flat bottom on the bottom cap.  It would have made it easier to fill the cap reservoir with storage solution and stand the unit upright.

I too was eyeing a white labs vial to convert into a storage solution reservoir.  Now all I need to do is make a stand for it.

Oh, and the reason I asked about the long-term stability of the solution was because the packets of 4.01 and 7.01 that shipped with the ph56 have expiration dates.  Mine expire in 7/2015, so I think I'll get a 230 ml bottle of each and it should last me several years.
Title: Re: pH Meters
Post by: punatic on March 22, 2011, 03:52:22 AM
The acidic pH 4 buffer/KCl storage solution keeps scale from building up on the pH probe's bulb.  This scale is what causes the pH meter to be slow to settle on the pH value as the probe ages.  Slow probes can also be revitalized by soaking them in a mild citric acid solution over night. 

Rinsing pH probes after every measurement is key to probe life.  Keep a squeeze-bottle of DI water at hand when measuring pHs.  Keep the pH probe wet at all times.  DI water is cheap.  pH probes are not.
Title: Re: pH Meters
Post by: johnf on March 22, 2011, 04:04:44 AM
I calibrate every day of use because, why not?

If I didn't I would at least check the pH of buffer if I got a suspect reading and I would calibrate daily for the first dozen or so brew days because otherwise I wouldn't be able to judge what a suspect reading was.

If you are worried about the cost, you can purchase pillows of powdered buffer that you mix with a measured amount of water. These can be much, much, less expensive than buying liquid at a home brew shop and may make you rethink the dollar cost of frequent calibration.
Title: Re: pH Meters
Post by: punatic on March 22, 2011, 04:32:23 AM
I calibrate every day of use because, why not?


We calibrate each pH meter at least once every workday, and record the calibration data in a logbook (spreadsheet).
Title: Re: pH Meters
Post by: bluesman on March 22, 2011, 12:59:04 PM
I calibrate every day of use because, why not?


We calibrate each pH meter at least once every workday, and record the calibration data in a logbook (spreadsheet).

+1

This is a good SOP if you want any degree of certainty in your measurements. Reliable data is good data.
Title: Re: pH Meters
Post by: Tim McManus on March 22, 2011, 02:02:28 PM
I just got an email from the folks at Milwaukee in response to some of the questions I asked on this thread.  They also sent a link to a video that shows how to calibrate the unit and change the temperature from °C to °F.  I thought I'd post it here in case some other folks had the same questions.

+++begin forward from Milwaukee

You should store in a cup or jar with about 1" of either storage solution, 4.01 calibration, a mix of 4.01 & 7.01, and last choice bottle water. Never let the probe dry out and be sure to rinse in clean water after each use -- you should also see our video at the following link:
 
http://www.milwaukeeinstruments.com/video-cal-pH55.html
 
This is the same calibration procedure for the PH56 as it is for the PH55
 
+++end
Title: Re: pH Meters
Post by: Kaiser on March 22, 2011, 02:58:56 PM
I calibrate every day of use because, why not?


We calibrate each pH meter at least once every workday, and record the calibration data in a logbook (spreadsheet).

+1

This is a good SOP if you want any degree of certainty in your measurements. Reliable data is good data.

I’d say that in my case pragmatism took over since it is extra effort for me to get out the calibration solutions, heat them to 25C and test the pH meter. Since I do that before experiments, the data for those needs to be more reliable than the pH readings for brewing, and I never had to change the calibration by more than 0.02 I stopped calibration and even checking before using the pH meter to take mash, wort or beer pH readings. If I get a much unexpected reading I’ll for sure check the calibration.

However, I do recommend that you start out with checking and calibrating the meter more regularly until you develop confidence that it doesn’t drift that much. With the automatic calibration meters I also suggest that you test the buffer before starting the calibration process. This way you can see how much off the pH meter was before it was calibrated again.

Interesting suggestion about storage in buffer, or a mix of buffer and storage solution. I learned something. From my experience I know that I have to regularly change the storage solution since I do get some mold growth.

As a side note, I’m actually very pleased how well my new pH meter (Milwaukee SM101) has been holding up over the last 2 years that I had it. The reading stabilized fairly quick (within 5-7s when testing wort or mash) and I have not seen a degradation of the slope (repeated need for calibrating the 4.00 point). All that after having easily done more than 1000 pH readings during experiments and regular brewing

Kai
Title: Re: pH Meters
Post by: mabrungard on March 22, 2011, 04:04:00 PM
I just got an email from the folks at Milwaukee in response to some of the questions I asked on this thread.  They also sent a link to a video that shows how to calibrate the unit and change the temperature from °C to °F.  I thought I'd post it here in case some other folks had the same questions.

You mean to tell me that Milwaukee has been paying attention to our forum?  If that's the case, I guess my next meter is going to be from them.

Title: Re: pH Meters
Post by: Tim McManus on March 22, 2011, 04:09:12 PM
I just got an email from the folks at Milwaukee in response to some of the questions I asked on this thread.  They also sent a link to a video that shows how to calibrate the unit and change the temperature from °C to °F.  I thought I'd post it here in case some other folks had the same questions.

You mean to tell me that Milwaukee has been paying attention to our forum?  If that's the case, I guess my next meter is going to be from them.




LOL, no.  I sent them an email yesterday afternoon and got the reply this morning.  Of course, they could be lurking...   ;)
Title: Re: pH Meters
Post by: Thirsty_Monk on March 23, 2011, 02:13:44 AM
Great video.
Thank you for the link
Title: Re: pH Meters
Post by: duxx on September 22, 2013, 10:26:42 PM
I'm hoping to purchase a pH meter in the near future.  I found this old thread.  So, I'm just checking to see if anyone has any additional comments, given that this is 2 1/3 years old?
Title: Re: pH Meters
Post by: mabrungard on September 23, 2013, 01:12:56 AM
I cannot recommend the PH56 meter, but I can recommend the MW-101.  I've heard of too many problems with the PH56. I do appreciate that I can replace the standard pH probe on the MW-101 since it is equipped with the industry-standard BNC connector.   
Title: Re: pH Meters
Post by: philm63 on September 23, 2013, 10:23:26 AM
+1 on the MW 101. Easy to calibrate, easy to use, good precision, good investment. As Martin said, replacing the probe is simple - many replacement probes have a standard BNC connector.