DO Meter Questions

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ajk
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Re: DO Meter Questions

Postby ajk » Thu May 19, 2016 10:35 pm

I'm getting high readings. Probably just my inexperience with the meter. I have yet to use it throughout the brew day, but some finished beers came out with high DO (~3 ppm). I don't think so because the malt and freshness from those beers is like a surreal trip through a wormhole directly to the Marienplatz. Willing to accept that I either need more time with the meter or need to work more on preventing oxygen ingress to the brewing process. We'll see ...
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ajk
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Re: DO Meter Questions

Postby ajk » Thu May 19, 2016 10:36 pm

Talking to Bryan and examining the meter, I think I have an air bubble in the membrane. Will correct and retry ...
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Brandon
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Re: DO Meter Questions

Postby Brandon » Fri May 20, 2016 8:43 am

" I don't think so because the malt and freshness from those beers is like a surreal trip through a wormhole directly to the Marienplatz." - that's the quote of the day! Maybe I need to post a Testimonials page. :)

I've gone through several membrane caps now. They get air bubbles very quickly, especially at high temps. I am instrumentally (or perhaps just mentally) challenged and have a heck of a time trying to get what I consider to be accurate readings with mine at low ppm. When in doubt, go with the results. I use the meter as a basic guide...if I see the numbers going lower with each brew I know I'm heading in the right direction.

Let me know if you need to try a spare cap, I have a bunch of extras.
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Bryan R
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Re: DO Meter Questions

Postby Bryan R » Mon May 23, 2016 7:56 am





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bensonledbetter
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Re: DO Meter Questions

Postby bensonledbetter » Thu May 26, 2016 2:40 pm

I was looking at the Extech DO600 specs and noticed something that I thought was kind of odd. Resolution is down to 0.01 mg/L, but accuracy is only +/-0.4 ppm (mg/L). This seems to imply that a reading of 0.2 could be off by as much as 0.4, meaning it could really be 0.6!

With that, how confident are folks that use this meter in readings on the low end of the scale? Seems like the absolute reading wouldn't be very useful in the low range, but instead trending the numbers might be insightful by highlighting points of oxygen ingress throughout the process.
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Brandon
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Re: DO Meter Questions

Postby Brandon » Thu May 26, 2016 2:48 pm

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Re: RE: Re: DO Meter Questions

Postby bensonledbetter » Thu May 26, 2016 3:06 pm

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Weizenberg
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Re: DO Meter Questions

Postby Weizenberg » Thu Jun 02, 2016 1:08 pm

The best ones are optical ones. The price tag
Is hefty though. There is an interesting thread on pro-Brewer where Mitch Steele asked about recommendations for a decent
DO probe....
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ephraim.greenblatt
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Re: DO Meter Questions

Postby ephraim.greenblatt » Sun Jul 03, 2016 3:40 am

New here. I've been obsessing over LODO for the past couple of weeks since I read your PDF. Thanks for your hard work.

Looking into a DO meter to get started. I know that you guys mostly went with the extech. This seems to be a polarographic meter with accuracy to .4ppm. I did some reading at http://www.fondriest.com/environmental- ... d-methods/.

The accuracy has been discussed above, but I am wondering about the constant stirring thing. From above: "If measurements are being done in a lab or still water, it is necessary to stir galvanic and polarographic DO sensors in solution. This measurement method is dependent on flow due to the consumption of the oxygen molecules 7. When the oxygen is consumed, the sensors can produce an artificially low DO reading in no-flow situations 7. Electrochemical dissolved oxygen sensors should be stirred in the sample until the dissolved oxygen readings no longer increase."

Also this. "When the instrument is turned on, it requires a 5-60 minute warm-up period to polarize the electrodes before calibrating or measuring." (from above link.)

I like accurate reliable measurements. A lot. I would pay more for a better meter, say up to $600.
I've seen this http://hannainst.com/products/benchtop- ... ge-do.html, it is also polarographic, but accuracy is .01ppm (am i reading this right?)
I also saw hach (a compay i love) has http://www.hach.com/hq30d-portable-mete ... 7640513820, but i need to call for a price.

Any thoughts?
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Re: DO Meter Questions

Postby Ancient Abbey » Mon Jul 04, 2016 9:19 am

Do what you think best, but I think you'll get a better return on spending that $600 on improvements we outlined (pumps, underletting, good QD fittings, etc.) than the meter. Otherwise, you'll spend $600 only to confirm you need to spend more money 8-) .
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