(First time) Building up RO water for an APA

The germs of this are in the book but have matured quite a bit since the publisher's deadline. The idea of using sodium bicarbonate as a titrant just came to me today (in the room where even the Kaiser goes on foot).

Well, add me to the future owner's club of the Hach meter after all.

afr0byte said:

I have a MW101, but I haven't had good luck with probes for some reason. I haven't used it much lately for that reason. I may have to retry, though. My basis for my supposed troubles was that I was getting a DI pH of around 5.6 for Weyermann Pils, whereas AJ had mentioned always gettings around 5.75. However, I saw a post recently where AJ mentioned getting a DI pH reading of 5.62 for Weyermann Pils? Fortunately I've been doing a lot of beers with similar grain bills (and always Rahr 2-row) so Bru'n Water has been close enough.

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It looks like your finding may be flawed. I would never have relied on the reading of an unknown substance to be the bases of a failure presumption. That is what those calibration standards are for!

While Yooper and others have had troubles with certain meters, the trend I note is that they all seem to be the 'all-in-one' style of meter. I have to refer to the seemingly universal practice in the pH meter industry for them to make their high end probes in the same form-factor. That is the typical cylindrical probe that is maybe 4 or 5 inches long and about 1/2 inch diameter. I assume this is because those probes are either: easier to make, or work better. In either case, I can't justify a move from this industry standard probe style. I note that the replacement probe costs for the Hach all-in-one is about 50% greater than the probe for the MW-101, so that is a minor black mark. More importantly, the perception I have from reading dozens of pH meter rants is that those meters are all-in-one types. That is the smoking gun that guides my recommendation.

mabrungard said:

It looks like your finding may be flawed. I would never have relied on the reading of an unknown substance to be the bases of a failure presumption. That is what those calibration standards are for!

While Yooper and others have had troubles with certain meters, the trend I note is that they all seem to be the 'all-in-one' style of meter. I have to refer to the seemingly universal practice in the pH meter industry for them to make their high end probes in the same form-factor. That is the typical cylindrical probe that is maybe 4 or 5 inches long and about 1/2 inch diameter. I assume this is because those probes are either: easier to make, or work better. In either case, I can't justify a move from this industry standard probe style. I note that the replacement probe costs for the Hach all-in-one is about 50% greater than the probe for the MW-101, so that is a minor black mark. More importantly, the perception I have from reading dozens of pH meter rants is that those meters are all-in-one types. That is the smoking gun that guides my recommendation.

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I agree it probably wasn't a great idea to base my conclusions on. I suppose I figured the DI pH wouldn't vary by .15 (since AJ has normally gotten a DI pH of 5.7/5.75 for that malt, and he likely has more accurate probes). I'll likely go back to using it, though I might get a new probe, since I'm not sure the storage solution hasn't dried out in my current one. Do you have a recommended probe for your MW101? Just the standard one? Where do you buy yours from?

Also, I suppose the MW101 is probably vindicated a bit, in my mind, in that AJ got a similar DI pH reading with the Weyermann Pils.

Checking the readings of the 2 calibration solutions after obtaining your mash reading(s) is the only way to be sure you can trust the #'s and correct for the drift. I'd trust your own numbers more than anything posted online if you know the state of your equipment and that the meter was shown to be in calibration before and after each reading.

DSmith said:

Checking the readings of the 2 calibration solutions after obtaining your mash reading(s) is the only way to be sure you can trust the #'s and correct for the drift. I'd trust your own numbers more than anything posted online if you know the state of your equipment and that the meter was shown to be in calibration before and after each reading.

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Agreed.

Reportedly, the probe for the MW-101 is filled with a gel and that may reduce the potential for dry out. However, we know that its best to keep probes saturated with a KCl solution. Based on some guidance found on the web, I heard that re-purposing your expired pH 4 calibration solution is the way to go. You add KCl to that calibration solution to make a 1 Normality KCl solution. I had a 500ml bottle of calibration std that was nearly full and I added the solid KCl to it. The one thing that I now hear recommended is to also add a bit of sodium benzoate to the solution to help avoid any biologic growth in the solution and on the probe. I still need to do that.

But with that big bottle of storage solution, I just cut a hole in the bottle cap so that the probe would fit snugly through and the probe is stored constantly in the solution when not in use. It has worked well.

Another thing that is easily accessible for probe maintenance is an enzymatic cleaner. AJ has mentioned using common enzymatic laboratory cleaners on your probe to remove growths and deposits. Well, those cleaners are typically sold in gallon jugs and they are more expensive and larger than I want to commit to. So another option for enzymatic cleaners are the typical fabric and carpet sprays. I already have Spray and Wash and spot cleaner for carpets in my household, so I have that covered. These should be acceptable cleaner solutions, but I haven't tested this out yet, so no guarantees! User beware. If anyone has a probe that they think has been compromised with protein growths or deposits, try out these cleaners along with a storage solution soak and report back here if they do or don't work.

Enjoy!

A couple of comments here some of which have probably been touched on earlier in this thread, others and the Sticky:.

It only makes sense to use the buffers for stability checks and 4 is better than 7 because reading at near 7 are insensitive to slope error. You also can determine the pH of a buffer as a function of temperature using formulas in the Sticky or buffer label information.


The DI pH of Wyermann pils malt has been measured near 5.6 and near 5.75. Obviously, it doesn't make a great standard.

I'm interpreting 'all in one' to mean the pocket style pH meter. I have bench-top meters that call themselves all in one because they meaure ORP, ISE, mV, conductivity, DO... There are several pocket meters that do more than just pH. I have seen plenty of complaints on the pen-type meters. Some of them cost $15. Can't expect much there. And I have seen complaints on the separate electrode meters. The common denominator seems to be 'cheap'. Cheap mean compromises are made to keep price low. As technology advances we hope that performance will continue to improve at the low price points. Keep your fingers crossed.

In re-examining the pen type pHEp meter sample I have I find it to be very stable but difficult to calibrate not because of stability but because of the algorithm. If I could decide when to accept the calibration reading rather than having the firmware do it I believe it would perform nearly as well as this new Hach (which does let me decide).

pH meters are sort of like digital cameras. Tremendous advances have been made in the electronics. It's not that big a deal to have 10 Mpixels with 10 bit depth... but all that doesn't matter if you put a cheap piece of glass in front. Much the same with a pH meter. It is the glass (electrode) that seems to be responsible for limitations in performance.

The form factor of the electrode doesn't matter much. I'm guessing the form factor of the traditionally shaped electrode is as much driven by old glass blowing techniques as anything else. The old ground glass renewable junctions would be hard to imagine in anything but a coaxial configuration. Other than that there is no reason that I can think of why the probe's internal electrode needs 5" wire leading up to it except that we need some way to allow the electrode to be immersed without allowing solution to access the connections.

I believe that the substantial recent improvements in meters are attributable to improved junction design and materials.

I may be a sucker for the guys in marketing but when I see that the replacement electrode for a meter costs well over half the cost of a new meter I interpret that to mean that most of the money has gone into the electrode which is where I think it should go.

I don't see much advantage to having a BNC connector on the meter/electrode except that I can use a Cole Parmer electrode on an Orion meter if I want to. Most of the newer meter's don't use BNC's for a couple of reasons the simplest of which is often that the RTD wires are run in the same cable as the pH wires and the most complex of which is that the electronics are in the electrode such that only digital data is transferred to the 'meter'. I can't use a Cole-Parmer BNC electrode on a Hach HQxxD meter. The other advantage of BNC connectors is that you can connect ORP or ISE electrodes if the meter supports mV and/or ISE reading modes.

Gel electrodes are less expensive to make and require less of the operator (you don't have to replenish the electrolyte) but once the electrolyte is exhausted the electrode is finished. Also, if the electrolyte gets contaminated or diluted you can't flush it out and renew it. If you store a gel filled electrode with solution that contains too much water, for example, water will flow into the gel and dilute it (I've seen this happen). That is why most storage solutions are saturated KCl (4.56 M) rather than molar. BUT if your manufacturer says to use 1 M storage solution, do it.

By immersing your electrode in storage solution and turning on the meter you can see whether the pH of the storage solution has been buffered and what it has been buffered to.

I don't think saturated KCl storage solutions contain mold inhibitors because I don't think anything will grow in saturated KCl (osmotic pressure?). I do think some buffers contain mold inhibitors and I think others don't (as I have seen mold grow in them).

Zymit is $33.50 /L from Cole Parmer. It's usually tough to find anyone who charges more than Cole Parmer and I've seen it for $30.95. You can also get it for $14.50/L if you have 11 buddies who also want a bottle from the case. OTOH I don't see why the enzyme based cleaners intended for home use shouldn't work.

AJ,

It's been about 9 months and I've just read this entire thread. What's the long-term opinion of the Hach meter you purchased?

Thanks,
Bob

Were I in Va I would go run another stability check on it but as I am not all I can say is it was hanging in there as of May.

Several reports from other users of units arriving bad or going bad have trickled in. The manufacturer has continued to resolve these cheerfully (including a case where the guy melted his by putting the batteries in upside down - you can't use a sailor proofing diode with a 3V supply) with one exception where it took a bit of pushing. The electrode is most likely to be the problem if there is a problem and that's warranted for 6 mos. There hasn't been much traffic on it here recently so I don't know if other people have been buying it nor what kind of luck they may have been having with it. Perhaps they will see your query and respond.

Thanks. I'm going to order this today. And I want to say thanks to you Martin (and BW) and all the others contributing to the collective understanding of water. I suggest there should be a dedicated sub-forum to All Things Water. I'm relatively new to this and I've been told I'm a little anal retentive, but I desire to understand the why's not just the how's. Again, thanks! - Bob

Just to chime in. I am one of the ones that had trouble with the Hach Pro+. The company response was outstanding IMHO. They sent me free buffer pillows (enough to last for years based on my use), cleaning solution, replacement sensor and finally a whole new unit. I have only had the new unit about a month. The stability check was good but I have only used it for one brew day and won't brew again for a month. The meter seems to have served it's purpose for me which was to establish some confidence in the spreadsheets (Bru'n water and Brewer's Friend). If the new one completely craps out not sure I would get another one (meter that is) since the spreadsheets are getting me pretty close. It is nice to have an actual reading though.

Hach Pocket Pro+ here as well. Stability check was solid and used it on my last couple of brews with no issues. I calibrate each time I brew, then check it again in the buffers once the brew day is complete and it has been within the specified range. I store it like AJ recommends with a few drops of DI water in the cap with no issues as of yet, but then again I have only had it a couple of months.

Finally received my Hach Pocket Pro+ meter. I put it together and soaked it in de-Ionized water for a few minutes per the manual I downloaded. The pamphlet that came with the meter was not as clear as I would have liked, so I opted for the online manual to make sure I did everything correctly.

In turning it on, the display looked normal (per the manual, and didn't say I needed to calibrate. So, I decided to measure the pH of my tap water (just tested at a pH of 7.9 by Ward labs). The meter immediately displayed a number on the top line, and a temperature on the bottom line with L, M, and H all illuminated in the middle (not sure this is right). The lower temperature line began to stabilize at 20C, but the pH line slowly started counting down to zero and then ultimately displayed "----" So, I checked the manual and it said "----" means the sample was out of range. Well, this is obviously not correct.

So I tried to calibrate using the pH 7.0 calibration solution that came in the box. and the exact same thing happened (but this time I was in calibration mode). It just counts down to zero and then goes to ---- in the display.

I've read the manual over and over and I don't see what else to do, but contact Hach for help.

You may indeed have a bad unit but it won't hurt to try a reset. Remove the batteries for about 10 minutes, reinstall them (be sure to get them in right - one guy on here didn't and carbonized his), turn the meter on and try to calibrate it.

rolomo said:

but the pH line slowly started counting down to zero and then ultimately displayed "----" So, I checked the manual and it said "----" means the sample was out of range. Well, this is obviously not correct.

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Given the meter is listed for pH 0 to 14 why is there even an option for "Sample was out of range"? I would really like to know what they thought you could test under zero or above 14. Having the manual blame you/sample is a bit bizarre.

You could test concentrated hydrochloric or sulfuric acids. Those both have pH's < 0

More to the point is that these platforms do other things besides pH such as conductivity. The firmware is set to detect, depending on the parameter being measured, any sensor voltage that is out of range for that sensor. For pH the voltage is ±7*58 = ±406 mV. If the sensor is working then any sample with pH < 0 or >14 would exceed that threshold and you would get the alert. If, as we suspect is the case here, there is a problem with the sensor a voltage with magnitude > 406 could be produced when 14 > pH > 0. You would still get the error message.

Hach is very responsive. They have suggested I clean the device, soak it in 7.0 solution for an hour and re-try.

They said to look for cracks in the sensor and test with 10.0 or 4.0 solution.

So, I need to get my hands on cleaner and more calibration solutions, before I can go any further. I'm guessing I'll have to order all this on line.

Will let you know what happens next.

AJ, Martin,

So.. I got my replacement Hach Pro+ pH Meter today.

Doesn't work. Similar problem, but different. I spent 1 hour with tech support. We tried all sorts of things. Sent them photos in real-time with both meters side-by-side.

I was certain when the second unit didn't work that it was operator error (and boy was I feeling like an idiot). But, in the end, they said the meter was also bad. They've asked for both back and sent me a free shipping label.

The are also sending me a third unit along with DI water and more 7.01 calibration solution.

I can't complain about their help - the chat and the tech support on the phone have been very nice and patient and knowledgeable.

I sure hope the third unit is the charm. Will let you know...

Bob

If it makes you feel any better I once went 5 rounds with Corning on a meter I bought from them several years back. They just kept sending me new electrodes until one that actually worked arrived. Hach is clearly having trouble getting this unit to market. It's been almost a year. Hach is definitely a good company(i.e. they have good customer service) but the fact that they are so willing to replace units tells us something.

Yikes. Every part of my engineering says that's bad business. I'm feeling much better!

If they believe the product has real potential then is is good business. They would expect a knowledgeable customer to understand 'infant mortality' and if they get past the point where their production/QC problems are solved such a customer has 1) a good product and 2) the impression that they stand by their products. Obviously this shipping out of replacement product can only go on up to a point beyond which they would have to accept that this design is flawed or that they are working with a supplier than can't make electrodes or whatever. When their tech spends a couple hours on the phone with you and has to send out 2 replacement units they are not making a profit - that's for sure even if they are able to send the bad units back for rework (and yours is the first case I recall where they asked for the return but perhaps others didn't report that they did).

Another update on my replacement meter from Hach. I've used it several times over the past couple of months. It hasn't gone haywire like the other one did which is good but it seems that every time I recheck my calibration @ PH 4 after checking my mash PH it ends up reading the buffer at 4.05. I'm super careful with the calibration procedure and waited a good 15 minutes before accepting the numbers this morning. It's done this every time now (I think) so there's a small but consistent drift occurring. I suspect checking the mash somehow throws it off a little. I washed it thoroughly before rechecking ect. It's not a major problem but something to note.

What happens if you let it sit in the pH 4 buffer for a few minutes (or is that what you mean by waiting 15 min before accepting the numbers)?

ajdelange said:

What happens if you let it sit in the pH 4 buffer for a few minutes (or is that what you mean by waiting 15 min before accepting the numbers)?

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I let it sit in the buffers for 15 minutes each for my initial calibration. After checking the mash I let it sit in the ph 4 buffer for about a half hour actually. It read 4.07-4.06 initially and then settled at 4.05 within a few minutes and stayed there.

That's weird. Wonder whether it is the slope or offset (or both) that is drifting and whether it is irreversible. As these meters don't display mV it would be hard to track that down.

I got my 3rd Hach Pro+ Pocket pH meter and finally had SUCCESS!!!!!

Calibrated in 7.00 and 4.01 (took only a few minutes) and then tested using same solutions and it was spot-on.

While I'm still amazed at receiving 2 bad units, I can't say enough about Hach. Ryan at tech support was very responsive, encouraging, and polite. They sent me, at no charge, a box of deionized water (large) and a full box of 7.00 singlets.

Looking forward to testing my mash today.




I love the Alchemy of it all!