Continuing pH metter issues

I got a Milwaukee pH56 last year for Christmas. I've had issues with it right from the start.

The first was that it took forever to calibrate and would drift. The pH readings were NEVER the same, even a minute apart. So, they sent me a new electrode. That one worked for a while, but about 5 months later it wouldn't calibrate. It read "wrng" whenever I placed it in the 4.01 buffer.

They offered to look at it, but told me a new electrode would be about $60. I am definitely not one to veto the experts, but I told the tech that this was the third electrode and so maybe it was a different issue? Well, they told me to send it in. They sent it back to me a week later, with no note. But I was assuming the electrode was replaced again.

I calibrated it about a week after I got it back, and it seemed fine. But about two weeks later I was having a brewday, and the meter would NOT calibrate. It says "wrng" when I placed it in the 4.01 buffer.

I knew the electrode was good, as I just got it back, so I spent $20 and bought new packages of buffer. I am trying to calibrate it today, and when I put it in the brand new 4.01 buffer, it reads "wrng". If I keep at it, it eventually does say "4.01 cal".

The electrode has never dried out, never been exposed to freezing or hot temperatures (room is 63 degrees), and I cleaned it today with the electrode cleaning solution, thinking that was the issue. It still is happening.

I'm an intelligent person, so it's not like I'm abusing this item and dropping it and expecting it to work. I've "babied" it, blotting only to wick up water when moving it, not exposing it to wort above 75 degrees, etc.

What the heck is going on? Is it possible to have such issues, and not have the problem be with the meter itself and NOT the electrode? It's more than a little frustrating, as it has worked correctly for maybe one month of the last year.

Some of these units can't single point calibrate other than 7.01. You can start a calibration at 7 and either stop there or finish with 4 or 10 for 2 point calibration. The warning signal may be a way to eliminate the user from mixing up the calibration solutions.

EDIT, looked at the manual for your unit and it can be calibrated with any buffer for a sinlge point calibration but needs to start with pH 7.01 for a 2 point calibration process.

http://www.milwaukeetesters.com/pdf/pH56_Manual.pdf

Yooper said:

What the heck is going on?

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I don't know and apparently they don't either.

Yooper said:

Is it possible to have such issues, and not have the problem be with the meter itself and NOT the electrode?

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Yes it is, unfortunately. Several years ago I bough a Corning pH meter that came with a defective electrode. So I complained and they sent me another one - also bad. I complained again and they sent me a third - also bad. When I called about this one they said they'd send me another. I asked if they didn't want to send the bad ones back and they said 'no'. I deduced from this that they had manufactured or bought a bad lot of electrodes and were willing to just keep sending out new ones until people quit complaining either because they got one that worked or got so frustrated they just threw the meter in the trash. I suspect that bad electrodes may be the case here. The 'wrng' message probably means that the voltage read in the 4.01 buffer is is either less than would be expected (given the temperature) implying the electrode has insufficient slope or that the reading is so erratic that the meter's stabilization criterion is not satisfied within a specified time period.

Now this doesn't mean that a problem with the meter itself isn't a possibility. As reliable as modern electronics are they still are subject to failures from bad bonding in an integrated circuit, conductive whiskers, a bad solder joint etc. All these things lead to the bane of people that have to work on electronic equipment: the intermittency. It works flawlessly in the shop but goes bad as soon as it is returned to you. I remember a colleague who was told by the maintenance people to quit bothering them about a signal generator as it was clearly working. He took it off the cart, dropped on the floor and said 'I don't think so.' (this was in the days of vacuum tubes).

Yooper said:

It's more than a little frustrating, as it has worked correctly for maybe one month of the last year.

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I don't doubt it! Perhaps it's time to cut your losses (financial and emotional) and get another meter from another manufacturer. All I can offer as a suggestion with respect to the one you have in hand is to remove the electrode, inspect the contacts and if possible (i.e. if they are reachable) rub them with a pencil eraser or shoot some compressed air in there. The idea is that the contacts may be making a poor connection because of dirt, dust, oil etc. You'd be amazed how many electronics problems come down to that. I've fooled a lot of people into thinking I am an absolute genius just by cleaning contacts when they were out of the room.

Damn, I just ordered a Milwaukee pH600-AQ meter. Hopefully I won't have the same problems. Will post my experiences.

You should insist on a replacement unit, preferably with a new warranty. They owe you. Escalate it on the phone and get a supervisor to promise not to send you the old one back. Stress that it’s second time in and has never actually worked properly.

The big chips are usually BGA (ball grid array) and sometimes they don’t seat correctly. Techs will reheat the chip and that usually gets it to work, but it’s not fixed.

ajdelange said:

The 'wrng' message probably means that the voltage read in the 4.01 buffer is is either less than would be expected (given the temperature) implying the electrode has insufficient slope or that the reading is so erratic that the meter's stabilization criterion is not satisfied within a specified time period.

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AJ, I'm really trying to understand that sentence. I think I've got it, but it took me about 6 reads.

Ok, dumb question here, then.

If I let it sit in the 4.01 buffer, it eventually loses the "wrng" message and seems to calibrate. It seems to drift slightly, but not too bad in a few minutes.

If I'm not ready to buy another (different) pH meter, is it possible that it is actually close to accurate after that 4.01 "wrng" message goes away and it gives me an "ok"? I mean, I only need to calibrate and take the mash pH. I can recalibrate for the sparge.

I'm really tired of dealing with Milwaukee Instruments and the emails and phone calls. It's also NOT in the budget to buy another pH meter at this time.

Is there a common household substance with a known pH so I can check my meter right after the half-assed calibration? White vinegar, diet coke, lye in water, etc?

Yooper said:

AJ, I'm really trying to understand that sentence. I think I've got it, but it took me about 6 reads.

Ok, dumb question here, then.

If I let it sit in the 4.01 buffer, it eventually loses the "wrng" message and seems to calibrate. It seems to drift slightly, but not too bad in a few minutes.

If I'm not ready to buy another (different) pH meter, is it possible that it is actually close to accurate after that 4.01 "wrng" message goes away and it gives me an "ok"? I mean, I only need to calibrate and take the mash pH. I can recalibrate for the sparge.

I'm really tired of dealing with Milwaukee Instruments and the emails and phone calls. It's also NOT in the budget to buy another pH meter at this time.

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Recalibrate before every measurement with these <$100 units.

Yooper said:

Is there a common household substance with a known pH so I can check my meter right after the half-assed calibration? White vinegar, diet coke, lye in water, etc?

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Well, a standard beer is going to have a finished pH of 4-4.5. You could try decarbonating a commercial beer or something. That might not be as accurate as you'd like though. Perhaps you could try starsan in distilled water? Maybe 5 Star lists the pH in distilled water, at the recommended concentration, somewhere?

Yooper said:

AJ, I'm really trying to understand that sentence. I think I've got it, but it took me about 6 reads.

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An electrode produces a voltage, in response to a given pH, of

E = Eo + slope*(pH - pHi)

where pHi is assumed to be 7. Slope depends on temperature but is about - 58 mV per pH. Eo is the 'offset' of the electrode and should be at most a few mV. For a pH 4 buffer then the voltage should be within a few mV of 174 mV. Slope and offset (Eo) both vary as the electrode ages. Nevertheless a meter expects to see something like 174 mV in pH 4 buffer. If it doesn't it thinks something is wrong and many meters will not let you perform a calibration if the slope appears to be less than 95% of the expected value. The other thing a meter expects to see is that the voltage stops changing within a few minutes. It declares readings stable when the voltage changes by less than a certain amount from reading to reading. If this doesn't happen (because of a noisy electrical connection, for example) the meter also cannot calibrate. A third thing I forgot to mention in the last post is a clogged reference junction. This is usually a little fritted piece that pokes out of the 'face' of the electrode near the bulb and the RTD. Fluid flowing through this frit conduct electricity thus closing the circuit. If it is blocked even partially current flow is impeded and erratic readings result. As this is a new electrode the reference should not be clogged but it can't hurt to look at it with a magnifier. I suspect that it is one or the other of these things that is causing you dismay.
Ok, dumb question here, then.

Yooper said:

... is it possible that it is actually close to accurate after that 4.01 "wrng" message goes away and it gives me an "ok"? I mean, I only need to calibrate and take the mash pH.

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There is an easy way to check and that is to read the buffers after calibration as if they were samples. You should get a stable reading close to what is on the pH package label for the temperature of the buffer. See the Sticky on pH Calibration for details.

I would expect that soda from the same bottler would have pH pretty closely controlled but I don't know what that pH is. The same is doubtless true for vinnegar made by the same manufacturer (and I don't mean balsamic) etc. but again I don't know what value to tell you. If I did a measurement here it might not apply where you live. And buffers are buffered i.e. are designed to hold a particular pH. It doesn't matter that that pH happens to be one that you used for calibration. We aren't questioning linearity here but rather slope, offset and stability.

ajdelange said:

There is an easy way to check and that is to read the buffers after calibration as if they were samples. You should get a stable reading close to what is on the pH package label for the temperature of the buffer. See the Sticky on pH Calibration for details.

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Yes, that's what I was doing today, and they (sometimes) seemed to read just fine. So I thought I could calibrate, and recheck the buffers, take the wort reading, and then recheck the buffer solution. I was hoping some smart person could say, "The pH of 5% white vinegar is 2.54" or something so I could see if I'm in the ballpark. I'm always looking for the easy way!

I've read the pH calibration sticky more than twice, just today.

Thank you so much for your help. I'll look at the meter tomorrow with a magnifying glass.

Forgive my late night math if this is wrong, but the best I can do for what you probably have laying around would be phosphoric acid. The pH of 10% (1.1 M) H3PO4 is about 1.07. Diluted 9:1 (90 ml distilled water to 10 ml 10% H3PO4) is about 1.61.

It's certainly well outside your calibration buffers but it might be a fun test. If your slope is whacky this should show it.

Speaking of phosphates, many brewers do have a phosphate buffer on hand in the form of 5 Star 5.2. It actually buffers to [Edit] 5.82 in distilled water as I recall but it is a buffer.

If I do the phosphoric acid calculations I come up with similar numbers varying a bit depending on whether I take ionic strength into account or not. But calculated values and measurements tend to differ as the low end of the pH scale is approached because of uncertainties about activity coefficients (I used the modified Debye-Huckle model which has been said to be accurate for slightly contaminated distilled water).

I have phosphoric acid on hand, and various other things. When I get a chance to play around with it, I'll play mad scientist and see what happens.

I'm planning on brewing on Wednesday, so maybe that will be "mad scientist" day.

Also maybe making sure an air bubble isn't trapped in the tube before the sensor.

Seems like kaiser had this problem also https://www.homebrewtalk.com/f11/buying-guide-ph-meter-127062/ I know you said a new meter is out of the question but he seems to have switched to a manual calibrating meter instead of an automatic one. I didn't read the whole article yet but I'm sure there has to be at least a little info in that thread to help you

Have tried doing a 2 point calibration starting with a 7.01 buffer?

helibrewer said:

Have tried doing a 2 point calibration starting with a 7.01 buffer?

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Me? Always. That's the first buffer I use.

I talked to Milwaukee Instruments today, and the asked me to send in the meter again. It just would NOT calibrate today. It eventually said "ok" after "wrong" on the 4.01 buffer, but it drifted badly.

This will be about $12 just on postage sending it back and forth. I realize that's not much, but added to the cost of the meter and the new buffers because I thought it was an issue possibly with the buffer solution, and fresh electrode cleaning solution, I'm in over $125.

A real incontinence but not bad customer service. It might be worth asking if an upgrade at a reasonable free to the MW102 based on the poor performance of your current unit is an option...

Sounds like you'll get a new unit anyway you go.

DSmith said:

A real incontinence ...

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Oh dear, I hope not!

Oops

Sounds like it could possibly be protein build up on the electrodes junction. Check your manual for electrode maintenance. If memory serves me correctly a strong alkaline solution will remove protein build up. Do you have access to some sodium hydroxide? If so make a 1M solution and soak the probe for an hour. Rinse well and try again.

Ladd said:

If memory serves me correctly a strong alkaline solution will remove protein build up.

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I was wrong, you need an acid not a base. Check out this link for general electrode care :

http://www.canadianwholesalehydroponics.com/electrodes.cfm

No way. I've had the unit back for two weeks, and it NEVER worked when it was returned. If there is a build up (how could that possibly be, having never been used?) that is up to the manufacturer.

I'm a nice person, and very tolerant, but the fact is this unit came back from them after testing and a new electrode but still never worked. My storage was appropriate, and it was never used. I'm not buying that I need to do anything.

I didn't realize that you hadn't used it since getting it back, if that is the case then it definitely is not the problem. I know though from personal experience that putting a pH probe into a solution that has a high organic or high protein content will foul the junction almost immediately, that is why I suggested trying to clean it. Also I just Googled your meter (I was posting from my phone the other night) and didn't realize it was a hand held. Our experience with handhelds at work has been all negative (sorry). We went through 4 or 5 of the Oakton's before we got frustrated and spent the money for a good meter (Corning 430). Hope you get it sorted out.

I haven't been around for a while but stopped in to see about getting a recommendation on what meter to buy myself for Christmas. My search foo must be weak. I'm not turning up any dedicated threads. Anyone want to throw out some models they have had good luck with? I'd like to stay in the $100 range if possible. Thanks.

I have 2 Hanna Checker meters that seem to drift endlessly. I am gonna try the Colorphast strips on the next brew day in comparison and then try the Milwaukee MW102 meter and if that fails I am gonna try liquid regents. If those options fail to produce a repeatable and useable result, then I will most likely give up on checking ph and rely on software to try to set the ph in recipe creation stage.

I have finally figured out that what is being given up in low cost meters is stability. Poor stability can be overcome by frequent recalibration. I know that is a real PITA but it does allow people to get decent readings with low cost meters. See the pH Calibration Sticky for how to do a stability check.

Obviously this thread isn't much of an endorsement for Milwaukee but some people have reported success with them.

Liquids aren't likely to work very well for this application as the color of the wort/mash will overwhelm the color of the dye used in the indicator.

It may not add much to help Yooper, but I'm actually very pleased with my SM101 from Milwaukee. It's a cheap ($80) meter with very basic functionality and it has been remarkably stable and reliable. After about 3 years I decided to change the electrode b/c readings took long to stabilize. Since the meter has a BNC connection for the probe I was able to buy a new one on Ebay. That one has been very stable as well. Just last night I checked the calibration and it was only off by 0.02 pH units. Last time I calibrated the unit was a few month ago (I'm getting lazy since I'm not doing many pH related experiments anymore).

A.J may disagree, but I think one can get decent brewing pH meters for under $100. I like the ones that don't have automatic calibration. I also used to have a PH56 and it was always a pain to get it to calibrate. I even went so far to forget about calibration and noted the pH readings for the 4.01 and the 7.01 buffers and had a little spreadsheet on my phone for correcting the reading.

Kai

Kaiser said:

After about 3 years I decided to change the electrode b/c readings took long to stabilize. Since the meter has a BNC connection for the probe I was able to buy a new one on Ebay. That one has been very stable as well.

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I think this is the key. It's pretty hard to design electronics that are unstable unless you are going between a cold room and standing next to the kettle. It is, IMO, the inexpensive electrodes that drift. If the meter is equipped with a BNC (but fewer seem to be these days) one has the option of buying a decent electrode to go with a cheap meter and this should solve most of the problem.

Kaiser said:

A.J may disagree, but I think one can get decent brewing pH meters for under $100. I like the ones that don't have automatic calibration. I also used to have a PH56 and it was always a pain to get it to calibrate. I even went so far to forget about calibration and noted the pH readings for the 4.01 and the 7.01 buffers and had a little spreadsheet on my phone for correcting the reading.

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I agree that one should be able to get a decent meter for under $100 - just not as stable as one might like but as I noted in a previous post stability can be gotten around by frequent recalibration or calibration checks.

I don't, however, understand the aversion to automatic calibration. It just makes life easier IMO but each to his own in this regard. I'll note that if you are 'correcting' by using the readings in two buffers you are in fact calibrating. Either you do it or the meter does it but it needs to be done. I'll also note that I don't use automatic calibration with one of my electrodes because it has an iso-electric pH of well over 8. The meter can't calibrate such an electrode so I do it in software. The process is as automated as I can make it. I put the electrode in 4 buffer and let the meter collect until the pH vs time history is flat, repeat in 7 buffer (or vice versa), position cursors over the flat parts of the pH response and hit 'calibrate'. All future readings are calibrated for those buffers and corrected for temperature.

I used my Hana pHep 5 (98128) last week by recalibrating with pH 4.01 & 7.01 buffers before each measurement, taking the measurement, and rechecking the calibration in the buffers for drift. In <10 minutes the meter read 4.00 & 7.05. That's ok drift for me and measurements mid-span are hardly affected. I have a spreadsheet tool for adjusting the actual reading to the post calibration check, but frequent calibration makes corrections very small.

Budget $40 for calibration buffers (4.01 & 7.01), electrode storage solution & electrode cleaning solution purchased with the meter. My meter is about 10 months old, only read room temperature samples, always kept vertical in cap full of storage solution, monthly cleaning solution and has proven reliable. Hana replacement electrodes are about $40 when the time comes.

I’m happy with my MW101, the one that replaced the SM101 that Kai has. I check it with the buffers but mostly don’t touch the calibration because it’s close enough. I feel bad that Yooper has had such grief with the pH56.

I’m beginning to think that it’s easier to make a decent electrode in a separate probe, standard parts and all. The proprietary pen models are trying to cram a lot into a small space.

Cleaner? I spray rinse with RO water, blot and put on the storage solution sleeve.

A wash-bottle (http://www.midwestsupplies.com/wash-bottle-500ml.html) with distilled water is nice for cleaning the meter when brewing and calibrating/rinising a refractometer.

The Hana electrode cleaning solution is per the instructions. I do an hour soak monthly.

I like equipment with separate readers/probes a lot too (do temperature measurements that way), but took a gamble on the Hana meter because there's no definitive advice about what to get and always the chance of getting a lemon. I don't regret that purchase 10 months later.

I have that same Hanna and don't seem to have a problem with it drifting, although I admit I have probably forgotten to use it more times than I've remembered! It seems to read about .02 higher than the Bru'n water spreadsheet would predict, but I have recently gotten a new version of the spreadsheet and am eager to give it a shot again.

I use distilled water to rinse between calibration solutions, and before putting away with storage solution. I haven't yet used the cleaning solution, but I've only used it about 5 times total so far. I think I got it for Xmas last year. or maybe my birthday this year (may).

In lab at school we have used Vernier LabQuest for making real time graphs of pH and temperature. The package is a bit pricey ($329) for the standalone unit, but I'm going to go the cheap route and buy their USB Go!Link, which is compatible with a lot of their probes, such as the temperature and pH ones. You just use their Logger Lite software on your computer so it can act as the standalone. I remember their pH meter working pretty well and being easy to calibrate. The really cool thing is that there are so many other cool sensors that can be hooked up to the link, such as:

Dissolved oxygen sensor
CO2 sensor
Calorimeter
Flow Rate
Calcium-Ion selective sensor
Salinity Sensor
Infrared Thermometer

The list goes on...I think I'm too excited about this! The link was about 60 bucks and I found the pH sensor for $20 on eBay.

I'll check in once I do some testing and let you know how it turns out.

ajdelange said:

I don't, however, understand the aversion to automatic calibration. It just makes life easier IMO but each to his own in this regard.

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Maybe its just a bad experience that I had with the PH56 which moved me away from auto calibration. I agree that it should make life easier. But it also adds to the price of the meter if you want to have a BNC connected probe, for example.

But you would agree that automated temperature correction is not needed in brewing use?

Kai

dbsmith said:

In lab at school we have used Vernier LabQuest for making real time graphs of pH and temperature. The package is a bit pricey ($329) for the standalone unit, but I'm going to go the cheap route and buy their USB Go!Link, which is compatible with a lot of their probes, such as the temperature and pH ones. You just use their Logger Lite software on your computer so it can act as the standalone. I remember their pH meter working pretty well and being easy to calibrate. The really cool thing is that there are so many other cool sensors that can be hooked up to the link, such as:

Dissolved oxygen sensor
CO2 sensor
Calorimeter
Flow Rate
Calcium-Ion selective sensor
Salinity Sensor
Infrared Thermometer

The list goes on...I think I'm too excited about this! The link was about 60 bucks and I found the pH sensor for $20 on eBay.

I'll check in once I do some testing and let you know how it turns out.

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That's great, but their webpage wants $130 for the ph sensor on top of the $61 for the goLink.
$160 for infrared temp sensor
$130 flow rate sensor
$209 DO sensor

eBay had the pH sensor for 20 bucks, making the total for a pH meter about 80 bucks, which is reasonable. I'm hoping that the other sensors might be able to be found on eBay periodically when I have extra cash to burn. Not having kids is great

Edit: Right now I see DO probes for about 60 bucks on eBay

Kaiser said:

But you would agree that automated temperature correction is not needed in brewing use?

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I guess I'd agree that you can get by without it but it isn't something that I would want to be without IOW I would never buy a meter that didn't have it unless I was planning to implement ATC on my own in which case the meter would have to have the ability to communicate temperature and mV readings to a computer and any meter that has that ability will also have the ability to do ATC. In other words ATC is automatically a part of any digital meter and I think the advantages of digital over analog are well enough understood that it's not necessary to restate them here. So if people ask 'should I get a meter with ATC?' I answer 'Get a digital meter and it will have ATC'. I've gotten arguments about that advice. There are still those that think analogue is superior to digital and that vinyl records sound better than CD's (they do sound better than CD's with mp3 music on them but that's another discussion).

But what does it mean to be without ATC? It either means that the effects of temperature are completely ignored or that temperature compensation is done manually. Would the consequences of this be dire? No, I don't think so. We are fortunate that we are critically interested in a region that falls half way between the pH's of the buffers we use for calibration. This happy circumstance leads to minimum 'dilution of precision' right where we want best accuracy IOW mismanaging temperature is not a serious problem. The actual contribution to error depends on the particulars of your calibration and measurement i.e. how different in temperature were the buffers, did you manually dial in temperature data, how did the sample temperature differ, what's the isoelectric pH of your electrode, did you ignore the change in buffer pH with temperature, how accurate are your temperature measurements. My overall philosophy is that with available buffers (± 0.02 pH) and reasonably accurate voltage and temperature measurement (0.5 mV, 0.5 °C) the limiting factor is the buffers. Given that I can expect, in that sweet spot, a standard error of 0.02 pH. Cognizant of the fact that this means that there is a 4% chance that my pH measurement of 5.50 is outside the band 5.45 to 5.55 and feeling, as I do, that 0.1 pH can have a noticeable effect on the outcome of a brewing session I don't want to give up any of the available accuracy. Therefore, as I get the error reducing advantages of ATC for free (especially if I do it myself in software) I always use it. Why not?

I'll be the first to admit that I am an 'accuracy freak' (a label pasted on me at the rifle range - not in the lab) and that my views are colored by my fascination with error sources and propagation so that if a reader has more relaxed views about how good a pH meter reading needs to be I won't disagree. I am definitely not saying people should take their non ATC pH meters and use them as Christmas tree ornaments henceforth but rather that if you find similar models of pH meters one with and one without ATC at a modest price differential, buy the one with ATC not so much because you are getting ATC as because this insures an all digital (as opposed to hybrid) design. If you need to stick to bare bones, get the one without. It will still be a valuable tool for you.