Hach pH Meter Questions

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Bassman2003

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Hello,

I am looking for a decent pH meter and came across the Hach name in some posts here. Seems like a good unit but which should I get?

Pocket Pro with a replaceable sensor or non-replaceable sensor? The price I saw was ~$95 or ~$65 Model numbers 9532000 or 9531000

Or is there a better choice for the $100 almost cheapo crowd!

Thanks
 
The most important difference is the accuracy.

http://www.hach.com/asset-get.download.jsa?id=18972203451

The 9531000's accuracy is .1 PH vs the 9532000's .02 PH accuracy (also the resolution is .1 vs .01).

I have the 9532000 (bought based on AJ's comments about it) and I like it a lot so far. I just calibrated mine today after doing it a couple of days ago and it was still within .03 of the calibration solutions. It's too new to know if that's normal but I was impressed with that.

Are you sure about the $95 price for the 9532000? The only price I could find was on the Hach site for $110 plus shipping. I was also later charged tax for a grand total of $137. http://www.hach.com/pocket-pro-ph-tester-with-replaceable-sensor/product?id=17990686211&callback=bc

There are only a few of us that have one so it''s hard to know how it will perform over time, but so far so good.
 
Hey thanks for the tip. I did not catch the accuracy differences. Looks like the 9532000 is the way to go.

The prices were shown on my screen a few weeks ago but since they have a lot of models maybe I was looking at different meters? I am travelling now and the prices are listed as "Contact Hach"...
 
The most important difference is the accuracy.

http://www.hach.com/asset-get.download.jsa?id=18972203451

The 9531000's accuracy is .1 PH vs the 9532000's .02 PH accuracy (also the resolution is .1 vs .01).

I have the 9532000 (bought based on AJ's comments about it) and I like it a lot so far. I just calibrated mine today after doing it a couple of days ago and it was still within .03 of the calibration solutions. It's too new to know if that's normal but I was impressed with that.

Are you sure about the $95 price for the 9532000? The only price I could find was on the Hach site for $110 plus shipping. I was also later charged tax for a grand total of $137. http://www.hach.com/pocket-pro-ph-tester-with-replaceable-sensor/product?id=17990686211&callback=bc

There are only a few of us that have one so it''s hard to know how it will perform over time, but so far so good.

Hi Jsguitar,

I'm about to pull the trigger on this one. I'll need some pH 4.01 and pH 7.00 buffer solution - do you recommend that I buy it from Hach? Whether or not to buy the "singlets" or the 500ml bottles is, I guess, a question of whether it ever expires - do you know?

Also, in the thread in which ajdelange "found" in started evaluating the Hach he mentioned that it does not require storage solution, so I guess I don't need any of that. Is there anything else I need to acquire at this time?

Peter
 
I've called the company twice and asked about the storage issue. The first time they told me to use the storage solution. The second time they said that they have been "arguing about it" around the office. The consensus was that you could store it with the storage solution or just a bit of tap water in the cap, just not DI water. I also asked about the premixed storage solutions versus the pillows that you mix yourself. They told me that the pillows were a good idea if you only use the meter/buffers every so often (I only brew about every 3 weeks if lucky). They said the premixed solutions are only good for a few months once you open them so unless you are using it a lot, no use buying a big batch of premixed stuff. The pillows are good for something like 4 years and you are only making about 50ml at a time. Way more cost effective I think. Ajdelange talks about some of this in his primer too. Good luck with the meter selection. I am happy so far with the Hach pro+ but I have noticed the temp reading is off about 4 degrees compared with my thermapen. That was the reason I called them today.
 
Thanks for the good info monkeyman, I've been wondering about the storage solution too. I also saw your post on the temperature. I'll have to check mine against my thermapen in a bit just to compare. I haven't bothered to do that yet.

pogden, as monkeyman hinted, you also need some DI water and ideally a washer bottle to rinse the probe and cap with. Also, AJ's sticky in this forum on calibrating PH meters is a good thing to read through.

I used mine Saturday during a brew session and then checked it back against the PH 4 buffer after and it was still within .01 of calibration. I'm going to check out the temperature accuracy though after reading monkeyman's comments.
 
Ok, just ran and checked the temperature against my recently calibrated thermapen and the meter read 61.9 and the thermapen was 62. I may just be lucky, but I'm not going to complain.

Edit: I was measuring my calibration solution.

Oh yeah, what did Hach say about the temperature discrepancy?
 
I was told by the guy today that it shouldn't be to much of an issue. He said the difference between what the pH would be if the temp was off by 4 degrees would be really small and that I could adjust the reading by looking at a chart to see what the difference would be. Not sure if I should be pissed about that or not now that I think about it. I will look at it again tonight to make sure I wasn't doing something stupid which is a definite possibility. I'm new to pH meters too so I'm just kind of bumbling along.
 
So I just rechecked it against my Thermapen. It read 65.9 and the Thermapen read 65 so not sure what happened yesterday. I wasn't even drinking.
 
So I just rechecked it against my Thermapen. It read 65.9 and the Thermapen read 65 so not sure what happened yesterday. I wasn't even drinking.

Well, there you go! I guess if there's a lesson to be learned its never, EVER fool around with a pH meter when you're not drinking.

Kidding aside, thanks for the discussion on this. I sort of assumed the premixed buffer would expire at some point, but I expected it to last a bit longer than 4 months. Pillows (or singlets) for me.

Do you guys just put the sample to be measured in the pH meter cap?
 
Jumping into an older post, but wondering if others have tried to order this meter? I am told that it is delayed for a couple weeks (mid-Feb).
 
Jumping into an older post, but wondering if others have tried to order this meter? I am told that it is delayed for a couple weeks (mid-Feb).

Just pulled the trigger on this. Hach quoted a one month lead time on this. Hopefully it's less than that... waiting for brewing equipment blows.
 
I ordered mine in mid-January and it is indeed on backorder. I called them last week and they told me that the anticipated ship date of 6 Feb still looked good. We shall see ... Waiting for being equipment definitely blows.
 
I've been doing AG for a bit now and am interested in tinkering with water additions and pH. I'm wondering if anyone has now tried the $70 Hach Pocket Pro pH meter (model no. 9531000)? I understand that it has a significantly lower accuracy (± 0.1 pH vs. ± 0.02 pH) than the $115 Pocket Pro + (model no. 9532000), but wonder how important that difference is in the context of mash pH measurements (i.e. if I get a reading of 5.2 with the cheaper meter, does it matter that the actual pH could be as low as 5.1 or as high as 5.3?) In other words, I'm wondering if the extra accuracy is really worth an extra $45, given that I'll be using the pH meter exclusive for homebrewing and won't have other occasion to take advantage of increased accuracy.
 
You really do need the resolution to see variations in the hundreths even though we are only worried about pH to about a tenth. The finer resolution enables you to discern where the pH is leaning instead of guessing if the pH was 5.44 (which reports as 5.4) or 5.46 (which reports as 5.5) or points between.
 
Well this is silly. I just realized that the response below is to an old post (#10) not the one pup up today. Nevertheless, here it is as it might be of interest to someone.

Remember that the Thermapen uses a thermocouple whereas the pH meter probably uses a thermistor or RTD and has, thus, the potential for greater accuracy which doesn't, of course, preclude the possibility of a defective RTD or thermistor. I would suggest calibrating the two meters with an ice water bath before drawing conclusions about either. This is a little trickier than it at first seems. You need a lot of ice in a insulated (e.g. styrofoam coffee cup, heavy ceramic mug) with enough water to fill the spaces between the ice cubes. What is often not stated is that you have to wait for the water and ice to come to equilibrium. The ice just out of the freezer is colder than 32 °F and the water is clearly warmer. After 5 minutes or more with gentle stirring insert the thermometer to be checked so that it only touches the liquid. FWIW my Thermopen reads 33.4°F in an ice bath and a Fluke Type K thermocouple (which is what I assume is in the Thermopen as well) with a Fluke multimeter reads 31.0 °F. These are typical Type K accuracies.
 
OK, now I'll respond to the current post:

I've been doing AG for a bit now and am interested in tinkering with water additions and pH. I'm wondering if anyone has now tried the $70 Hach Pocket Pro pH meter (model no. 9531000)? I understand that it has a significantly lower accuracy (± 0.1 pH vs. ± 0.02 pH) than the $115 Pocket Pro + (model no. 9532000), but wonder how important that difference is in the context of mash pH measurements (i.e. if I get a reading of 5.2 with the cheaper meter, does it matter that the actual pH could be as low as 5.1 or as high as 5.3?)
In the case of the Pro + we know exactly what the accuracy specification means as Hach sets it out clearly in the 'manual'. BTW this is the only time I have ever seen the meaning of a pH meter manufacturer's definition of accuracy stated. It means that a freshly calibrated electrode returned to one of the buffers with which it was calibrated will give, over a specified period of time, readings whose RMS error is the stated value. Thus if they quote 0.01 (and as I remember that's the value given for the +) the standard deviation in a reading's error (if made withing the spec time frame) will be 0.01 pH. The plot in the post at https://www.homebrewtalk.com/showthread.php?t=302256 shows what this means. There we see errors of up to 0.03 though most are less than that. The square root of the sum of the squares (RMS) is, however, less than 0.01 and so the 0.01 accuracy spec is met.

(i.e. if I get a reading of 5.2 with the cheaper meter, does it matter that the actual pH could be as low as 5.1 or as high as 5.3?)
Or more. Imagine the errors in the plot in the Sticky to be 10 times what the scale indicates. Thus would imply accuracy of 0.1 pH rather than 0.01 using the numbers as plotted.

The interpretation of all this is that, as modern digital electronics don't drift, that accuracy is really completely (or mostly) determined by the stability of the electrode.

Electronics manufacturers don't like to build 10 different instruments for a line of products. It is often much less expensive to build one an 'cripple' some of the functions it is inherently capable of. Hach may (and I emphasize may) be doing something like this by which I mean the whole line may be one circuit. If one orders the pH only version the conductivity circuit may be disabled and a pH electrode slapped on the thing and it ships as a Pocket Pro + if it meets the 0.01 spec. If it doesn't, then move a jumper (which disables the hundredths digit and renders it a Pro rather than a Pro +) and send it to shipping. Just speculating here but I do feel quite assured that if you go with the cheaper unit you will have an unstable (to the extent of 0.1 pH standard deviation) meter and you will realize that 'the bitterness of poor quality remains after the sweetness of low price is forgotten).


In other words, I'm wondering if the extra accuracy is really worth an extra $45,
Yes, it absolutely is. Though you don't need 0.01 or 0.02 absolute accuracy in brewing you do want to be able to see the effects of water or mash treatments to that level and, therefore, need the higher resolution/accuracy/stability.

..given that I'll be using the pH meter exclusive for homebrewing and won't have other occasion to take advantage of increased accuracy.
You might be surprised.
 
Thanks ajdelange for the detailed response. I'll try to summarize to check for comprehension:
  • The Pro should generally return results accurate to ± 0.1, but could occasionally be off by ± 0.3 or more because of the way accuracy is established for these devices. As I understand it, 0.3 is potentially meaningful in brewing water pH, so the occasional outlier reading in terms of inaccuracy could end up making a material difference.
  • Accuracy to ± 0.01 allows for fine-grain tweaking of water chemistry through small treatment additions without overshooting (which could be a problem even at ± 0.1, and certainly at ± 0.3).
  • The Pro could contain the same hardware as the Pro+, but that failed to meet Pro+ accuracy requirements (i.e. the meter was designed for accuracy to ± 0.01, but was "defective" by that standard though still meeting the ± 0.1 standard of the Pro). Am I right that you view this as a problem distinct from the stated level of accuracy, because a "defective" unit may have other problems or may grow more inaccurate over time?

Based on this analysis, you have no reservations about recommending the Pro+ over the Pro, despite the cost differential and even if I won't be using the pH meter for anything other than hombrewing (who knows, but as of now I can't think what else I'd want it for!)
 
Holy $#]€! Same AJ that gets mad props in The Water Book. I'll be damned.
 
Thanks ajdelange for the detailed response. I'll try to summarize to check for comprehension:

Based on this analysis, you have no reservations about recommending the Pro+ over the Pro, despite the cost differential and even if I won't be using the pH meter for anything other than hombrewing (who knows, but as of now I can't think what else I'd want it for!)

I'm not sure why you're downplaying using it for home brewing. I have the pro+ and only use it for homebrewing (and cider). When I use it I'm not just looking to see what the mash pH is. I'm looking at how much acid I had to add to get to a certain mash pH. I then adjust future brews accordingly. If I had a pH meter that had a resolution of +/-0.1 (or worse...) I wouldn't have a clue about the effects of my acid / mineral additions.

If you want to take the opinion of a random on the internet I see the options as not buying a meter or buying the 0.01 resolution one. The 0.1 should not even be on your radar - that is a waste of $70.

I work in a measurement science field (surveying) and I wouldn't try to measure to 0.01m accuracy with a tape measure that only measures to 0.1m.
 
[*]The Pro could contain the same hardware as the Pro+, but that failed to meet Pro+ accuracy requirements (i.e. the meter was designed for accuracy to ± 0.01, but was "defective" by that standard though still meeting the ± 0.1 standard of the Pro). Am I right that you view this as a problem distinct from the stated level of accuracy, because a "defective" unit may have other problems or may grow more inaccurate over time?
Yes but do keep in mind that this is pure speculation on my part.

Based on this analysis, you have no reservations about recommending the Pro+ over the Pro, despite the cost differential
Correct

and even if I won't be using the pH meter for anything other than hombrewing
(who knows, but as of now I can't think what else I'd want it for!)
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