Author Topic: other methods of taking gravity readings  (Read 1264 times)

Offline KCguy

  • Cellarman
  • **
  • Posts: 95
other methods of taking gravity readings
« on: April 11, 2019, 12:06:37 PM »
I usually use the old fashioned hydrometer, but its always bothered me how much wort it sacrifices.  And even though Ive sanitized it beforehand, I never trusted pouring that back in the fermenter.  O2, infection...too many risks there...

Also tried a refractometer, but misunderstood and later learned it was only intended for use before adding yeast; I wanted to take readings throughout fermentation.

I guess my question is does anyone take frequent readings to monitor fermentation and if so, how if different than the above types. 
Drinkin Tripels, Seeing Double, Feelin Single...

Michael B
Kansas City

Offline KellerBrauer

  • Brewer
  • ****
  • Posts: 345
  • Bottoms Up!
Re: other methods of taking gravity readings
« Reply #1 on: April 11, 2019, 12:24:30 PM »
Using a hydrometer is the most accurate way of checking gravity, unless you spend loads of money on an electronic device.

Even though you need a lot of wort to check gravity using a hydrometer and a sample tube, the wort can be dumped back into the boil kettle with no ill effects.  However, after fermentation begins, I use a beer thief to grab a sample, drop in my hydrometer and take a reading.  When I’m done, I dump the sample onto a small tasting glass and drink it. The sample is about 3-4 oz.

https://www.amazon.com/Fermtech-Wine-Beer-Thief-Long/dp/B00BTMWXC6/ref=sr_1_3?crid=979XE15U7GHS&keywords=beer+thief&qid=1554985069&s=gateway&sprefix=Beer+theif%2Caps%2C1279&sr=8-3

Check it out.
All good things come to those who show patients and perseverance while maintaining a positive and progressive attitude. :-)

Offline KCguy

  • Cellarman
  • **
  • Posts: 95
Re: other methods of taking gravity readings
« Reply #2 on: April 11, 2019, 12:45:43 PM »
Even though you need a lot of wort to check gravity using a hydrometer and a sample tube, the wort can be dumped back into the boil kettle with no ill effects. 

Wait - you're taking readings of hot wort?  Ive never heard of doing that - is it somehow telling you the efficiency of the wort?  Doesnt the temperature change the reading? 

I have a thief too, but the amount of wort still is too much for me.  I drink it also, it doesnt go to waste, just wish there was a better way....
Drinkin Tripels, Seeing Double, Feelin Single...

Michael B
Kansas City

Offline Big Monk

  • Brewmaster
  • *****
  • Posts: 681
  • I’m Derek Scott. I’m a Category 26 kind of guy.
    • Low Oxygen Brewing
Re: other methods of taking gravity readings
« Reply #3 on: April 11, 2019, 01:17:51 PM »
Even though you need a lot of wort to check gravity using a hydrometer and a sample tube, the wort can be dumped back into the boil kettle with no ill effects. 

...is it somehow telling you the efficiency of the wort? 

I mean, technically speaking, knowing your gravity DOES tell you your efficiency.

Doesn't the temperature change the reading? 

Yes. You have to correct using the following:

S.G. Correction Factor = 1.00130346-(1.34722124*POWER(10,-4)*°F)+(2.04052596*POWER(10,-6)*POWER(°F,2))-(2.32820948*POWER(10,-9)*POWER(°F,3))

So if you measure your wort at 158 °F and get a reading of 1.045, the actual S.G. reading is going to be 1.067.

You can also use a refractometer, although you have to know the correction factor for your unit beforehand. You can get a good estimate by measuring known solutions of water and sugar and then substituting the correct correction factor for the wort gravity you are aiming for.
“We are what we repeatedly do. Excellence, therefore, is not an act, but a habit.” Aristotle
"Messieurs, c’est les microbes qui auront le dernier mot." Louis Pasteur
Check out The Brewing Troubleshooters at https://brewingtroubleshooter.yolasite.com/

Offline Robert

  • Official Poobah of No Life.
  • *
  • Posts: 4002
Re: other methods of taking gravity readings
« Reply #4 on: April 11, 2019, 01:55:07 PM »
I use a refractometer now throughout the brewing and fermentation process.   I do still have a good set of narrow range, professional, brewery saccharometers (Plato hydrometer with built in thermometer and correction scale.)  I long fancied the idea of using a refractometer for the ease of use and small sample size,  but I had given up on my old hand held, optical refractometer. It was quite untrustworthy.  But I have a digital refractometer now,  and it turns out there is no such thing as a "correction factor for the unit."  I'm now convinced that the origin of the idea of such a correction among users of hand held optical units is in fact correction for the vagaries of the users' eyeballs. The digital one works perfectly, measurements confirmed by saccharometer.  You can in fact take readings through fermentation,  but you do need to correct for the presence of alcohol or the reading will be not just inaccurate but completely meaningless.  Read the article on refractometer use by Petr Novotný in the July/August 2017 Zymurgy.  The free calculator at Brewer's Friend uses his equation, if I'm not mistaken.  I've incorporated it into my own spreadsheet and found it to be quite reliable.
« Last Edit: April 11, 2019, 02:00:21 PM by Robert »
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline case thrower

  • Assistant Brewer
  • ***
  • Posts: 214
  • NE Ohio
Re: other methods of taking gravity readings
« Reply #5 on: April 11, 2019, 03:13:00 PM »
Rob, do you have a link for the digital refractometer you use?  And are there any concerns about using it at higher temperatures?
Dave C.

Woke up this mornin' and I got myself a beer.
The future's uncertain and the end is always near.

Offline Robert

  • Official Poobah of No Life.
  • *
  • Posts: 4002
Re: other methods of taking gravity readings
« Reply #6 on: April 11, 2019, 04:56:48 PM »
Rob, do you have a link for the digital refractometer you use?  And are there any concerns about using it at higher temperatures?
It only takes a couple of drops of wort on the prism, so that cools mighty fast.  And the unit has automatic temperature correction  built in, in case it's still a different temperature than when calibrated with distilled or RO water.  I believe MoreBeer sell this too, maybe labeled as a wine refractometer.   The instruments are identical AFAIK, just one calls the readout Brix and the other Plato.  So you could compare prices between MoreBeer and the manufacturer.

https://hannainst.com/hi96841-digital-refractometer-for-beer.html
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline dmtaylor

  • Official Poobah of No Life.
  • *
  • Posts: 3707
    • Manty Malters - Meet the Malters! - Dave Taylor
Re: other methods of taking gravity readings
« Reply #7 on: April 11, 2019, 06:19:22 PM »
Refractometer works just fine as long as you learn your correction factor (mine is 0.99) and use the Brewer's Friend calculator or equivalent.  The website does explain how to figure out the correction factor.

https://www.brewersfriend.com/refractometer-calculator/

Also I love my new Tilt, which monitors SG the whole way, though it is a bit finicky.
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline spurviance

  • Cellarman
  • **
  • Posts: 60
Re: other methods of taking gravity readings
« Reply #8 on: April 11, 2019, 08:33:44 PM »
Also I love my new Tilt, which monitors SG the whole way, though it is a bit finicky.

What is finicky about the Tilt?  I am an extreme tightwad but if I was going to splurge on a brewing accessory this might be the one as it seems to solve all the above mentioned issues with refractometers and hydrometers.
On tap,  Vienna Lager, Doppelbock, Dortmunder Export, Pale Ale, Porter, Saison

Fermenting, Saison

Offline BrewnWKopperKat

  • Assistant Brewer
  • ***
  • Posts: 207
Re: other methods of taking gravity readings
« Reply #9 on: April 11, 2019, 08:57:48 PM »
After working with new technology on weekdays, I like the idea of an 'old fashioned hydrometer' when I'm brewing on the weekends.  No correction factors to calculate, no WiFi or Bluetooth connections to troubleshoot (and no batteries to charge  ;) ).

So when I'm brewing "house" recipes, I'm brewing to a desired result (12-pack, 24-pack, ...).  I'm working towards scaling up recipes slightly to include some extra wort for the a couple of hydrometer measurements.

With new or experimental recipes, I'm less concerned about hitting the desired result - if I have to take an extra hydrometer measurement (and come up a bottle sort), that's OK.

 
« Last Edit: April 11, 2019, 08:59:28 PM by BrewnWKopperKat »

Offline dmtaylor

  • Official Poobah of No Life.
  • *
  • Posts: 3707
    • Manty Malters - Meet the Malters! - Dave Taylor
Re: other methods of taking gravity readings
« Reply #10 on: April 11, 2019, 09:25:04 PM »
Also I love my new Tilt, which monitors SG the whole way, though it is a bit finicky.

What is finicky about the Tilt?  I am an extreme tightwad but if I was going to splurge on a brewing accessory this might be the one as it seems to solve all the above mentioned issues with refractometers and hydrometers.

The Tilt requires Bluetooth technology and/or faulty phone app... which for some reason tends to get disconnected every 2-6 hours, at least that's been my experience but I know for certain I'm not the only one, I've heard reports of same or similar from several others.  This means we need to manually unclick and re-click the Bluetooth connection every so often to re-establish connection.  Not a real big deal unless you're going to be away for a whole day and REALLY NEED to know the exact SG at all times..... personally I don't sweat it too much, I just enjoy seeing the trend and knowing when to change temperature or dry hop or whatever.  On the other hand, you're about equally likely to be one of the lucky people who never have this problem.  Flip a coin.  Maybe you'll be lucky.  I'm never so lucky.

Another thing is that for good accuracy, it needs to be calibrated, and re-calibrated, and re-re-calibrated, prior to every use, IF you want it to be very accurate within 0.001-0.002.  If that level of accuracy isn't important, great, skip the extra calibration steps and you'll still be happy.  But if you're retentive like I am, the extra calibration necessary is a little bit of a pain.  Personally I'm pretty content (so far, anyway) to deal with it because to me it's worth the little extra effort.

The other touchy thing with Tilt is that after it has krausen and/or hops stuck to it, it tends to read low by approximately 0.002 or thereabouts (in my experience).  But as long as you know this, you can easily correct for it at the end of fermentation.  You can gently shake the fermenter to get some of it off, or just live with a reading that's a little off.

Alternatively........ I really really REALLY love my refractometer, now that I know how to use it correctly.  See link from my previous post above.  It's friggin awesome, and accurate within 0.001-0.002 every time without a lot of extra calibration steps.  A couple drops and you're good to go -- how easy is that!  And cheap!
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline tommymorris

  • Brewmaster General
  • *******
  • Posts: 2336
  • Tommy M.
other methods of taking gravity readings
« Reply #11 on: April 11, 2019, 09:53:12 PM »
Also I love my new Tilt, which monitors SG the whole way, though it is a bit finicky.

What is finicky about the Tilt?  I am an extreme tightwad but if I was going to splurge on a brewing accessory this might be the one as it seems to solve all the above mentioned issues with refractometers and hydrometers.
Readings are sometimes affected by the krausen sticking to it. Supposedly that resolved itself once the krausen drops.

I have one but have not used enough to comment.

Correction: you calibrate the Tilt in water. Not with a hydrometer. I am getting old and remembered wrong. Scary.
« Last Edit: April 12, 2019, 03:10:59 AM by tommymorris »

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 4610
  • Ask me why I don't like Chico!
    • SeanTerrill.com
Re: other methods of taking gravity readings
« Reply #12 on: April 12, 2019, 12:15:58 AM »
Read the article on refractometer use by Petr Novotný in the July/August 2017 Zymurgy.  The free calculator at Brewer's Friend uses his equation, if I'm not mistaken.

Just be aware that Petr's correlation is targeted at being accurate for fermenting wort, not for precision FG readings.
Sent from my Microsoft Bob

Beer is like porn. You can buy it, but it's more fun to make your own.
Refractometer Calculator | Batch Sparging Calculator | Two Mile Brewing Co.

Offline Robert

  • Official Poobah of No Life.
  • *
  • Posts: 4002
Re: other methods of taking gravity readings
« Reply #13 on: April 12, 2019, 12:32:21 AM »
Read the article on refractometer use by Petr Novotný in the July/August 2017 Zymurgy.  The free calculator at Brewer's Friend uses his equation, if I'm not mistaken.

Just be aware that Petr's correlation is targeted at being accurate for fermenting wort, not for precision FG readings.
I do get accurate FG values with his formula though.  Confirmed with measurements by a hydrometer/ saccharometer/ floaty thing, they're within the margin of my ability to read said floaty thing accurately. In fact one of the advantages I see in a refractometer is that it's not lifted up by bubbles, and I don't have to worry about seeing it through hazy beer or foam. 

When I was going through a long period of acclimation and convincing myself a refractometer would really work, I found the two most reliable formulas, about equal, to be his and one of yours.  I can't remember which of yours, except that I don't think it was your "new cubic."  Anywho, it's consistent and more than good enough, since I don't need to satisfy the revenuers as to the alcohol content of my beer anyway.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline dmtaylor

  • Official Poobah of No Life.
  • *
  • Posts: 3707
    • Manty Malters - Meet the Malters! - Dave Taylor
Re: other methods of taking gravity readings
« Reply #14 on: April 12, 2019, 01:10:25 AM »
The most accurate formula for me is "Old Cubic", by a hair.  But I did steal and customize Mr. Terrill's spreadsheet and for that I am very thankful.   8)
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.