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Home Brew Forums > Home Brewing Beer > Brew Science > Cheap pH meter by EtekCity - Any good?
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Old 01-16-2014, 07:30 PM   #11
ajdelange
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AJ, I'm still waiting on someone to tell me that they have had problems with the MW-101.
You can look at the reviews on Amazon (http://www.amazon.com/Milwaukee-MW10...DateDescending). Of these the most interesting is the one that gives it a 5 star rating but says that you have to recalibrate before every reading (in all caps). Or you can look here. Yooper, for example, has had a terrible time with hers. No one has published stability test data on one. I'd be curious about that (especially given that 5 star review).


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Since I deal with the wastewater industry, I know that having a double junction style pH probe is critical for extending the probe's life.
In wastewater perhaps. Actually, as silver and protein can complex one might think that a double junction design would be important in brewing as well and there was a time that I would definitely have recommended a double (and renewable) junction. But the electrodes I am using today, with unbelievable success in brewing are not, as far as I can see in peering through the plastic wall, double junction. So I no longer recommend double junction specifically but rather a junction that is free from clogging problems in the brewing environment.


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The MW-101 is so equipped.
That is good, of course, but may be immaterial in terms of today's junction technology.

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In addition, it is a gel filled unit that apparently improves its longevity.
I was reading somewhere recently (the Hanna website?) that gel filled electrodes last longer. How can this be? When the electrolyte is depleted it is depleted and you have to throw the electrode a way. With a refillable, you just top off occasionally and Bob's your uncle. Perhaps the greater flow tends to keep the junction clear (so that double junctions are no longer needed) but I really suspect that it is something in the frits themselves - a new super no-stick material of some sort. Just speculating here. That same site said that one of the advantages of double junction technology is that it is cheaper to manufacture. If that's true all these meters have double junction references (but I don't think so).



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Be careful in recommending Omega. They often just re-badge other manufacturer's equipment for their low-end equipment.
So does Hach and so do many, many other major manufacturers. I took apart a Hach meter once and found the board silkscreened Orion. Their spectrophotometers are obviously made by Beckman. I am perfectly happy to have rebranded gear made by reputable manufacturers but I do wish there were more transparency. Today this is very common practice. If you want to sell a pH meter is it smarter to start from scratch or go to someone with years of experience in building pH meters and have them build it for you? Which is likely to produce the better meter? Not to mention that the meter contains an instrumentation amplifier from one chip supplier, an A/D converter from another and a microprocessor from a third... The key is the electrode. Who makes the electrode? The meter itself is just electronics and firmware. There is art in the electrode.

All this shouldn't be taken as an endorsement of the Omega as I don't know anything about it (though the first pH meter I ever brewed with was an Omega instrument - and rebranded at that). What I do know is that there is now a promising looking meter for $110 (the Hach) which appears to represent a step forward in the art. Which is why I am tentatively recommending it. I just showed it to a guy at the local Gordon Biersch and he ordered one. I anxiously await his review. He'll put it through the wringer for sure.

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As AJ says, you generally get what you pay for.
And I still do - at the $13 level and, in most cases with the older technology meters, even at the $70 - $80 level. I still think that saving $30 on an old technology analog meter is a false economy. I used to think you couldn't get into a 'good' pH meter for under $250 but am, of course, very hopeful that the Hach and perhaps the Omega and then others will prove that, as is so often the case with technology, performance goes up and cost comes down. I'm now buying 3 TB disks for just over $135 (?).
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Old 01-16-2014, 08:01 PM   #12
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Wow. Some great feedback guys! appreciate it.

AJ, I like your reasoning. I've been instilling it in my wife's brain that I can now brew 5 gallons for around $10-15 since I'm washing yeast now, too, but for me, it's always a tough justification. I still have several hundred bucks in equipment, and want to spend several hundred more! I just bought my all-grain setup for $500 from a guy on CL a couple months ago, so I feel like that's still too close to the top of the registry If I do buy one, I'll be sure to let you know what I think of it.

Martin, Good to know. Sounds like you know a lot about pH meters. I'm just getting started here, so I really appreciate the look into them. What seems important to me is 1) replacable probes (surprised at how many low ends don't...) 2) Accuracy at least .02 and 3) some good reviews/recommendations. If I do end up buying one, I'll definitely give you guys some honest feedback on it.

Again, it's hard because it seems a good piece of equipment is a couple of hundred dollars. I was really hoping there was an 'industry standard' amongst homebrewers for pH meters (like the STC-1000 for temp control or March 809 for pumps). In homebrewing, there are so many other expenses. I could easily burn up $1000 bucks tomorrow, and not even think about pH meters. Between a kegging setup, fermentation control, brewpot accessories, electrical components, pumps, HERMS, etc, I have a hard time prioritizing one piece of equipment that gives me one data point. Obvously I'd like one eventually, but as it grows more expensive, it moves down my list.

I may be getting ahead of myself with the chemistry side. I am just on a chemistry kick lately i guess. just started the chemistry of brewing course through OU, and have been digging into water chemistry. (BTW read your BrunWater spreadsheet Martin, and that was very helpful).
I think I'll just estimate using Bru'nWater and other resources for a while first and see how my beers turn out. I think I have at least a beginners understanding of water chemistry in general, so I think I'll just start some basics like adding a bit of acid to the mash if I have a lighter grain bill, and making sure I build up my Calcium levels as well as Chlorides or Sulfides (depending on style) with salts. The one thing that still hasn't really clicked for me is Alkalinity... I have 55-75 mg/L (as CaCO3), which seems relatively low. So that means I may not need as many acids in my mash as some because there is less buffer (resistance to pH), correct? (Bru'n water should tell me, just trying to wrap my brain around it I guess).

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Old 01-16-2014, 09:10 PM   #13
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I have 55-75 mg/L (as CaCO3), which seems relatively low. So that means I may not need as many acids in my mash as some because there is less buffer (resistance to pH), correct? (Bru'n water should tell me, just trying to wrap my brain around it I guess).
It's actually quite simple once (as is so often the case) the light comes on. Everything that goes into your mash has a pH higher (water, base malt..) or lower (acid, dark malt, acidualted malt...) than the desired mash pH. You must add protons to the items with higher pH and absorb protons from the items with lower pH in order to get to mash pH. Clearly the high pH items can absorb protons from the items with lower pH. The mash pH is the pH at which the protons emitted just equals the protons absorbed.

Alkalinity is the number of protons required to change the pH of 1 liter of your water to 4.5. The number is multilplied by 50 in the US so 75 mg/L as CaCO3 is equivalent to 75/50 = 1.5 mEq/L. As you don't need to take your water to pH 4.5 but rather only to pH 5.4 or so you don't need 1.5 mEq/L protons for the water but more like 1.35 (assuming your water's pH is 7). If you had 19 L (about 5 gal) you'd need 25.6 mEq. Your base malts will levy similar requirements and their proton deficits as well as that of the water must be overcome. This you have to do by adding protons from a bottle (a bottle full of acid is a bottle full of protons) or by adding malts whose dough-in pH's are less than the desired final mash pH. The less alkalinity you have the fewer protons you need to take care of the water.
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