pH Meter Calibration

ajdelange said:

Try soaking the probe in a solution of Zymit or a similar enzyme based cleaner.

Click to expand...

That's definitely worth a shot, the Milwaukee cleaning solution has worked great for my 102 probe. My current probe is going on 4 years now. When I feel the response slows I'll soak it for a couple DAYS. The response improves noticeably, but is less effective each time. I can still get a stable reading in 10-15 seconds but I feel this one won't survive in my brewery much longer. The drift has gotten a little worse but still usable. I'd say 4 years for this kind of probe is impressive. I'd have tossed this after 2 years without a regular cleaning regimen.

That pH probe is on sale, but I am going to pass on it for now, BRS runs sales all the time.

I am going to try the Milwaukee Cleaning solution.

I just ordered it from amazon for 14 bucks. Give that a shot, if that doesn't work, I will order a new probe and make sure I use the cleaning solution regularly in addition to my normal procedures. So the cleaning solution won't go to waste.

Thanks all
-Craig

View attachment ImageUploadedByHome Brew1465153788.557450.jpg
That was with my Thermoworks 8682.
Columns would be time, ph, temp
I was scared at first. But once the temp stabilized, the ph did as well.

The problem was the las measurement. Changing quickly between those two values.
I left the meter in the solution the whole time, turning on the meter to take a measurement and turning it off after that.

Rinsed with tap water after the weird measurement, and tried to calibrate with buffer 7, but also got crazy readings. Now I rinsed it again with tap water, then a bit of destiled water and put it away in storage solution.
I'll try again later in the day.

Anything wrong in my procedures? If not, what do you think about the stability of this model? I think that if I leave the samples to stabilize the temp before taking the first measurement it would be much more stable.

I finally made the leap and purchased a pH meter under $100.

I first set the calibration according to the manual. The calibration was only off by .05 on both solutions. I then ran the stability test using the same fluid I set calibrations with. In between tests I rinsed with ro water that had a pH of 5.38. I stored the meter in the supplied solution provided in between each test after rinsing with ro water. the meter has a resolution of .01 and accuracy of .02+/-.

7 Technical Specifications
Model P771 pH Meter
Range 0.00 ~ 14.00 pH
Resolution 0.01 pH
Accuracy ± 0.02 pH
ATC Range 5 °C to 50 °C
Operating
Environment
5 °C to 50 °C
0 to 90% R.H.
Storage
Environment
0 °C to 50 °C
0 to 90% R.H.
Power Two 3V Lithium (CR2032) Batteries
Expected Battery Life 100 hours continuous
Display 3 ½ digit
21 x 18 mm LCD (.8 x .7”)
Dimensions 33.5 mm x 170 mm (1.3 x 6.7”)
Calibration Manual, 2 point, through offset and slope trimmers
Weight 85 g (3 oz)
Housing ABS IP57

Time 7buffer 4buffer solution temp
1:20pm 7.00 4.00 77deg solution room temp was swinging from 77/74
1:22pm 6.98 4.01 78
1:33pm 7.00 4.01 77
1:43pm 6.98 4.02 78
1:51pm 6.99 4.02 78
2:01pm 7.00 4.02 78
2:12pm 7.00 4.02 78
2:25pm 7.00 4.02 78
3:16pm 7.00 4.02 78
4:16pm 7.01 4.02 77
4:55pm 6.99 4.02 78

I will continue stability test but thought the results were very promising.

6-25
6:00am 7.00 4.02 78
1:19pm 7.01 4.02 78
5:13pm 7.00 4.02 79

vbwolpert said:

I finally made the leap and purchased a pH meter under $100.

I first set the calibration according to the manual. The calibration was only off by .05 on both solutions. I then ran the stability test using the same fluid I set calibrations with. In between tests I rinsed with ro water that had a pH of 5.38. I stored the meter in the supplied solution provided in between each test after rinsing with ro water. the meter has a resolution of .01 and accuracy of .02+/-.

7 Technical Specifications
Model P771 pH Meter
Range 0.00 ~ 14.00 pH
Resolution 0.01 pH
Accuracy ± 0.02 pH
ATC Range 5 °C to 50 °C
Operating
Environment
5 °C to 50 °C
0 to 90% R.H.
Storage
Environment
0 °C to 50 °C
0 to 90% R.H.
Power Two 3V Lithium (CR2032) Batteries
Expected Battery Life 100 hours continuous
Display 3 ½ digit
21 x 18 mm LCD (.8 x .7”)
Dimensions 33.5 mm x 170 mm (1.3 x 6.7”)
Calibration Manual, 2 point, through offset and slope trimmers
Weight 85 g (3 oz)
Housing ABS IP57

Time 7buffer 4buffer solution temp
1:20pm 7.00 4.00 77deg solution room temp was swinging from 77/74
1:22pm 6.98 4.01 78
1:33pm 7.00 4.01 77
1:43pm 6.98 4.02 78
1:51pm 6.99 4.02 78
2:01pm 7.00 4.02 78
2:12pm 7.00 4.02 78
2:25pm 7.00 4.02 78
3:16pm 7.00 4.02 78
4:16pm 7.01 4.02 77
4:55pm 6.99 4.02 78

I will continue stability test but thought the results were very promising.

Click to expand...

Can you use the storage and cleaning solutions from one manufacturer with another?
I have the M102 and my LHBS only carries Hanna products.

Most (note that I did not say all) storage solutions are saturated potassium chloride in water so storage solutions typically are interchangeable but you should check on this. There are plenty of Milwaukee and Hanna users here so you should be able to find out which uses what.

Cleaners should be interchangeable.

On storage of the Hach meters...

"QUESTION: How should pH probes be stored best?
ANSWER: All Hach pH probes are delivered with a plastic protection cap that can also be used for storage. Pour a few drops of saturated KCl solution into the cap to ensure that the glass membrane is kept hydrated and ready to use. For short-term storage of a few hours, the pH probe can be placed in a solution of 3.5 molar KCl or pH 4.0 or pH 7.0 pH buffer. Always rinse before use. As a general rule, pH probes (especially reference probes) should never be stored in deionised water. Overnight, the probe should be stored in the corresponding electrolyte storage solution, usually saturated KCl. For long-term storage (2 weeks or more), the pH probe should be stored with its protection cap filled with storage solution and sealed with Parafilm."

When they say "cap filled with", do they mean literally filled or just a few drops as has been mentioned in this thread?The FAQ appears to give contradicting information.

I would tend to think they mean enough to keep the probe end submerged.

It is generally enough to keep the probe hydrated and this is often done with nothing more than a little sponge in the end of the protective cover which sleeve is saturated with saturated KCl solution and the protective cover slipped on so that the bulb is in contact with the sponge. The more sophisticated (equals expensive) Hach electrodes come with a 'soaker bottle' which is a bottle that holds a few mL of storage solution and which has a hole in the screw on cap large enough to pass the probe body and and O-ring arrangement of some sort to make a seal. With these the business end of the electrode is submerged in KCl solution.

An exception to this is the meter most commonly used by people here: the pH Pro+. Its electrode is covered by a plastic cup which also serves as a sample holder. With these one need not use special storage solution. Distilled or even tap water will do and you only need a couple of drops in there - enough to keep the relative humidity inside the cap near 100% so the electrode does not dry out. Even if it does that's not a problem and Hach was recommending dry storage for quite a while after they put this meter on the market.

With these latter meters I reason that you don NOT want to have much storage solution in the cap as you do not want the storage solution to reach the junction. If it does, the thinking goes, as the osmotic pressure of the water outside is greater than that inside water will move in and K and Cl ions will move out thus reducing the effectiveness of the reference half cell.

Thanks for the input. I just got my Hach pH Pro + and now I need some buffer solution. Great info here as always.

I just got my pocket pro + and have been walking around the house with it around my neck like a dog with a new bone. My head is so big I'm not even sure I need this forum anymore but I'll stick around for the benefit of my fans.

Having said that....err...how do I know when it has "stabilized". It beeped at me once which I thought was its way of showing me affection...clearly we've bonded but wtf was it telling me besides the fact I have a nice butt?

I bought my pocket pro a year ago in May (17 months ago). The last two mashes I noticed that the pH reading was much different (lower) than before. This past Saturday, when I calibrated it, it kept drifting down slowly (about 0.01 every 20-30 seconds). After I finally calibrated it, I checked the pH 7 buffer again and it was off by 0.2 units .

So I have ordered a replacement probe ($90+ including shipping ).

I kept it stored as recommended with just a few drops of water in the cap. I used it probably 25-30 times before it crapped out.

Any suggestions on how to make this new one last longer?

$90?? That's one of the problems with proprietary equipment. There is something to be said for generic or universal equipment standards.

dunbruha said:

Any suggestions on how to make this new one last longer?

Click to expand...

Probably not. You stored it as the manufacturer recommends. It's more or less of a crap shoot from there. We have noted that Hach did have problems with electrodes when they first brought this product to market but they are supposed to have been solved. Thus the next one may last longer simply because of that. OTOH it might not. How long did it last?

ajdelange said:

Thus the next one may last longer simply because of that. OTOH it might not. How long did it last?

Click to expand...

I sure hope so! It lasted 17 months.

checking my MW101 for the first time and can't find the stability test link. Started recording my numbers every minute but not sure I'm doing it right. AJ, or anyone else could you post the link on how to do the stability check? then I could post my findings. Thanks

No need as you are already here. The test is described in the first post in this thread.

Is there any more feedback on the Omega model mentioned in this thread? I'm ok spending $100+ on a decent quality PH tool but would prefer to not have to spend upwards of another $100 on replacement probes considering I only brew about 12-15 times a year.

Hannabrew said:

Is there any more feedback on the Omega model mentioned in this thread? I'm ok spending $100+ on a decent quality PH tool but would prefer to not have to spend upwards of another $100 on replacement probes considering I only brew about 12-15 times a year.

Click to expand...

Which model Omega meter are you speaking of?

jpb2716 said:

Which model Omega meter are you speaking of?

Click to expand...

Omega PHH-7011

That's the meter that I have. I love it. If you're only doing 12 or so batches a year, you won't need to change out the probe for many many years

I wouldn't count on that. Electrodes tend to age out rather than wear out. That said I've had electrodes go more than 5 years. I wouldn't count on that though.

So I purchased the Hach Pro Plus and did my first brew with it. I think I did everything right and after taking a ph reading 15 min into the mash (after a good stir) my reading came out to just about exactly what Bru n Water suggested it would be.

Since I use a cooler mash, one thing I'm struggling with is how to take these ph readings without losing heat. From what I've read I need to wait until at least the 15 min mark to take a reading and potentially should be taking it more than once yet everytime I open the lid I'm letting out a ton of heat and I noticed my mash dropped 2 degrees from just one reading.

Any suggestions?

Hole (normally closed with a stopper of some sort) in the lid and a wine thief?

ajdelange said:

Hole (normally closed with a stopper of some sort) in the lid and a wine thief?

Click to expand...

I suppose that's a good plan but then I'm breaching the lid. I guess it boils down to if the multiple pH readings are worth the potential temp loss of altering my lid?

I'm assuming a reading in the beginning of the mash after a hearty stir is not good enough right?

I've been thinking about the same issue... Would there be any reason that taking a sample from the spigot on the mash tun wouldn't work?

rprego said:

I've been thinking about the same issue... Would there be any reason that taking a sample from the spigot on the mash tun wouldn't work?

Click to expand...

My thought is that the water that pools under the FB is not a good example of the rest of the mash. And that's even with some pump recirculation in the beginning of the mash. When I go to vorlauf it is usually clear for the first pint or so.

A hearty stir or two or seven throughout the whole mashing process is a good idea from the POV of the mash itself but also in terms of getting a representative pH reading. This is the problem with drawing from a single point (i.e. the output tap which is otherwise a good suggestion) but obviously, in a situation where even opening the lid results in excess heat loss, is not a good idea unless one were to open the lid, take the sample, add a bit of boiling water, stir and close the lid. If you can't do that (too full) it would be a good idea, both from the POV of mash performance and sample integrity, to pick up the cooler and slosh the contents around before taking a sample (wine thief or spigot).

I like the idea of adding some boiling water each time I open it. I suppose I'd have to figure out what works for my setup. Could I just "borrow" from the sparge water?

Where did The Forum land on storage of the Pro+? I've seen a couple of differing opinions posted and didn't know if there is a consensus amongst the group. I'm currently storing it with a bit of RO water however it is drying up quickly so I'm concerned about it drying up and me not knowing until it's too late

I'm going to assume the advice is still to store in the cap with some water.

I tried doing a stability test last night and realized how much of a noob I am at this. I have a few questions I was hoping to get answered.

1) If my storage water dries up, what is the best way to rehydrate the bulb? 10-15 minutes in tap water?

2) I'm using premixed buffers and I realize that for calibrating I will always want fresh buffers however for the stability test do I need fresh buffers for each testing? If so, it seems like I'll use my whole bottle before the stability test is through!

3) How do I know when a reading is stabilized? When I put my meter into the 7 solution for calibration it started at 7.12 and gradually kept climbing down and never seemed to stop. I gave up when it was at 6.91. Every time I thought it had stabilized it would drop another tenth. This was over the course of about 5 minutes. It never stayed on any given reading for longer than a minute though.

4) When rinsing with DI water, how important is it to get all the water out of the sample cup? I've been pretty OCD about it but I'm wondering if I need to be...is it the PH of any risidual water we're worried about affecting the buffer or the dilution of it? As for the meter itself, I've been spraying it and as AJ mentioned just using a paper towel to wick at it without putting any pressure on the bulb.

5) Once I calibrate 7 and 4 and save, shouldn't my reading be 4.00 if it's still sitting in the buffer? I was getting 3.99 (which I realize is within the accuracy range just thought it would show exact right after calibration).

6) When I put the meter in the sample, should I move it around before locking the cap on or lock the cap on and then shake it around?

7) I RTFM and didn't see anywhere that mentioned where we could find the slope/offset values on this meter...correct me if I'm wrong. If we don't know what it's using, how do I know that the meter is calibrated any given time I turn it on? Do I just plan on calibrating every day/time I use it?

8) with ATC, do I need to be concerned with the temperature at all when recording the readings? I will always cool my samples down to room temp (~70F) but want to make sure that the slight variances shouldn't matter. Assuming ATC accounts for temp differences, why do we need to chart temp when doing a stabilization test?

9) Other than spraying with DI water right after use, is there any need for cleaning solution? I think I read in this thread it was unneeded but just wanted to verify.

I think that's all for now. Thanks in advance.

-pHNoob

Hannabrew said:

I'm going to assume the advice is still to store in the cap with some water.

Click to expand...

Yes.

Hannabrew said:

1) If my storage water dries up, what is the best way to rehydrate the bulb? 10-15 minutes in tap water?

Click to expand...

Or RO water or DI water or 7 buffer,

Hannabrew said:

2) I'm using premixed buffers and I realize that for calibrating I will always want fresh buffers however for the stability test do I need fresh buffers for each testing?

Click to expand...

You want fresh buffers each time you run a test but for a single test just put the electrode in 4 buffer, stir occasionally and record displayed pH.

Hannabrew said:

3) How do I know when a reading is stabilized? When I put my meter into the 7 solution for calibration it started at 7.12 and gradually kept climbing down and never seemed to stop. I gave up when it was at 6.91.

Click to expand...

You record every 5 minutes or so. What you are looking for is it stabilizing. It should stop stabilize after a few minutes. An erratic history is indicative on an unstable meter/electrode and one that is, therefore, innaccurate.

Hannabrew said:

Every time I thought it had stabilized it would drop another tenth. This was over the course of about 5 minutes. It never stayed on any given reading for longer than a minute though.

Click to expand...

Not a good sign. The sticky has a plot from a stable meter.

Hannabrew said:

4) When rinsing with DI water, how important is it to get all the water out of the sample cup? I've been pretty OCD about it but I'm wondering if I need to be...is it the PH of any risidual water we're worried about affecting the buffer or the dilution of it?

Click to expand...

Yes, it is responsible for 'dilution error' but that shouldn't amount to a hill of beans. Turn the cup upside down and rap it on the counter. That should get 99.9% of the rinse water out.

Hannabrew said:

As for the meter itself, I've been spraying it and as AJ mentioned just using a paper towel to wick at it without putting any pressure on the bulb.

Click to expand...

Should be fine.

Hannabrew said:

5) Once I calibrate 7 and 4 and save, shouldn't my reading be 4.00 if it's still sitting in the buffer? I was getting 3.99 (which I realize is within the accuracy range just thought it would show exact right after calibration).

Click to expand...

Were the noise figure of your meter 0 and the electrode perfectly stable, yes. O/W no. A drift of 0.01 is perfectly acceptable as long as you stay near 3.99 for a half hour or hour or two.

Hannabrew said:

6) When I put the meter in the sample, should I move it around before locking the cap on or lock the cap on and then shake it around?

Click to expand...

Either.

Hannabrew said:

7) I RTFM and didn't see anywhere that mentioned where we could find the slope/offset values on this meter...correct me if I'm wrong.

Click to expand...

Don't believe this meter displays either. That is usually a feature of more expensive meters.

Hannabrew said:

If we don't know what it's using, how do I know that the meter is calibrated any given time I turn it on? Do I just plan on calibrating every day/time I use it?

Click to expand...

Yes, recal, or at least do a cal check, every time you use it. When the electrode wears out the meter will tell you it can't cal.

Hannabrew said:

8) with ATC, do I need to be concerned with the temperature at all when recording the readings?

Click to expand...

Yes, because the pH of the buffers change with temperature. Try to hold buffer temp constant during a stability test.

Hannabrew said:

9) Other than spraying with DI water right after use, is there any need for cleaning solution? I think I read in this thread it was unneeded but just wanted to verify.

Click to expand...

I have not found it necessaary even with electrodes I have used for years but that doesn't mean that you won't.

Thanks AJ...so since this is brand new, should I reach out to Hach about exchanging it since it doesn't appear to cal properly (constantly drifting downwards)?

Yes, I would.

I finally bought a pH meter -- the Hach Pocket Pro+. I was surprised that it only had one little packet of 7.00 buffer solution (I thought there would be a packet of 7 and a packet of 4 so you could do a 2-point calibration). So I'll need to buy some buffers sooner than I expected. What are the shelf lives of premixed buffers, a year? 2 years? Not sure what size bottles to get, 250ml or 500ml.

I have the same meter. If you fill to just below the line on the sample cup, that's 10 milliliters.
If you brew 20 times a year and check the calibration every session that's 200 ml.
I've been buying sets of 250 ml bottles here.
They have at least a one year validity period. I think that might be typical of pre-mixed test solutions...

Cheers!

Link doesn't work. How about these?

https://www.amazon.com/dp/B01F7OXRG2/?tag=skimlinks_replacement-20
https://www.amazon.com/dp/B017H73794/?tag=skimlinks_replacement-20

I thought it took a lot more than 10ml per sample.

DOH! Apologies for the stupid link trick (fixed).
This three solution kit is what I've been buying...

Cheers!

Used to use another set of (Nelson-Jameson) buffers, and never stored in storage solution - stored in pH4 solution, though I think I did titrate make up a solution at some point.

Any thoughts on this solution (I'm getting the Hach as well, though I used to use the Extech).