Strangely low SG reading part way through fermentation

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guypettigrew
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Re: Strangely low SG reading part way through fermentation

Post by guypettigrew » Tue Dec 08, 2020 10:43 pm

Not sure what the 'python version' is, but here's how to do it from a PC.

Open Beer Engine. At the top you should see a bar with 'File, Printing, Calculators, Editors, Help'.

Click on 'Calculators'. The drop down has seven items. The sixth is 'refractometer'. Click on this. It gives you a pop up box cunningly entitled 'Refractometer'!

In the bottom left corner is a '?'. This gives you Graham's write up. Just below the top is a bar labelled 'set calibration factor'. The way you use it is explained in the write up.

Hope this helps.

Guy

Jase
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Re: Strangely low SG reading part way through fermentation

Post by Jase » Wed Dec 09, 2020 11:48 am

Hi Guy,
ok, thanks. that makes sense. The Python version is the "Wheelers Wort Works" version, which was re-rwritten in python after Graham Wheeler moved on. It is linked at the top of the forum extras page. It looks like that version doesn't have the refractometer feature....which explains why I couldn't find it...
I should have just downloaded GW's original verision...
Thanks
J

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Eric
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Re: Strangely low SG reading part way through fermentation

Post by Eric » Wed Dec 09, 2020 2:29 pm

Jase wrote:
Wed Dec 09, 2020 11:48 am
Hi Guy,
ok, thanks. that makes sense. The Python version is the "Wheelers Wort Works" version, which was re-rwritten in python after Graham Wheeler moved on. It is linked at the top of the forum extras page. It looks like that version doesn't have the refractometer feature....which explains why I couldn't find it...
I should have just downloaded GW's original verision...
Thanks
J
Isn't it still there? I thought it was.

Currently brewing and using a refractometer.
Without patience, life becomes difficult and the sooner it's finished, the better.

Jase
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Re: Strangely low SG reading part way through fermentation

Post by Jase » Fri Dec 11, 2020 12:10 pm

Eric wrote:
Wed Dec 09, 2020 2:29 pm
Jase wrote:
Wed Dec 09, 2020 11:48 am
Hi Guy,
ok, thanks. that makes sense. The Python version is the "Wheelers Wort Works" version, which was re-rwritten in python after Graham Wheeler moved on. It is linked at the top of the forum extras page. It looks like that version doesn't have the refractometer feature....which explains why I couldn't find it...
I should have just downloaded GW's original verision...
Thanks
J
Isn't it still there? I thought it was.

Currently brewing and using a refractometer.
Not that I can see. Just a File menu, and then the main tabs. Went through it several times, but maybe I missed it.

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Eric
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Re: Strangely low SG reading part way through fermentation

Post by Eric » Fri Dec 11, 2020 6:10 pm

https://www.jimsbeerkit.co.uk/extras.htm

and listed second is............"Download Graham Wheeler's Original'Beer Engine' Recipe Calculator - the last version ever issued by Graham himself"

which takes you to

https://www.jimsbeerkit.co.uk/BeerEngineSetUp.exe

which presumably Jim hosts on this site.

Just loaded it on an old Windows 7 machine and it worked fine for me.
BE.jpg
Have another try.
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Re: Strangely low SG reading part way through fermentation

Post by guypettigrew » Fri Dec 11, 2020 9:05 pm

Nice straightforward recipe, Eric. I'm guessing you've brewed it. How did it turn out? Mind if I nick it for when I've got some Fuggle hops in?

Sorry to slightly hijack your thread, Jase.

Guy

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Eric
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Re: Strangely low SG reading part way through fermentation

Post by Eric » Fri Dec 11, 2020 11:09 pm

guypettigrew wrote:
Fri Dec 11, 2020 9:05 pm
Nice straightforward recipe, Eric. I'm guessing you've brewed it. How did it turn out? Mind if I nick it for when I've got some Fuggle hops in?

Sorry to slightly hijack your thread, Jase.

Guy
No Guy, it isn't mine and I've not brewed it, but one of the custom recipes included by Graham. I wouldn't brew it that way in any case as Graham used Black Malt and white sugar to replicate Invert sugars which he assumed would be out of the reach of most home brewers. As it happens I have inverts 1, 2 and 3 by Ragus in stock, but mostly attempt inverting cane sugars with added molasses which generally never reach the quality of the real article, but are vastly cheaper.

A mild is in the brewing programme for January, but sadly it won't be 5% ABV.
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Re: Strangely low SG reading part way through fermentation

Post by guypettigrew » Fri Dec 11, 2020 11:48 pm

Oh, that's a bit embarrassing! I've never looked at Graham's 'Example recipes' before.

Invert sugar is something I'd like to try, but never have. It's difficult to find in home brew quantities. I seem to remember Ragus only sell it in fairly huge amounts.

Guy

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Eric
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Re: Strangely low SG reading part way through fermentation

Post by Eric » Sat Dec 12, 2020 12:04 am

25 kg blocks by Ragus, supplied to home brewers by Bako. If you buy any, don't say it is for brewing as it is then subject to VAT. There is no VAT on it for baking purposes and that will save you 20%. Ragus supply direct to the larger breweries, but only to a handful of traditional brewers remain. I've not been advised of any micro breweries that use it, but I hope some are. It does make a different and better beer that can't be produced with other ingredients. It is much more expensive than using malted barley, but using between 10 and 20% takes the beer into a different league.
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Re: Strangely low SG reading part way through fermentation

Post by guypettigrew » Sat Dec 12, 2020 12:23 pm

Thanks Eric, but 25 kg is too much. Unfortunately I don't know any other home brewers round here who I could do a joint order with.

Guy

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Re: Strangely low SG reading part way through fermentation

Post by McMullan » Sat Dec 12, 2020 1:37 pm

25kg sounds like a lot, but if you end up adding some to most English brews it soon gets used up. The shelf life is very long, years. It is a shame all-grain brewers tend to shun the use of sugars generally. As an invert convert I totally agree with Eric. I'm glad I was persuaded to try it. Most of my brews now contain homemade invert cane sugar.

This Mild (from Ron Pattinson's excellent book Let's Brew!) is currently fermenting nicely:

Name %/IBU
Maris Otter (Crisp) (7.9 EBC) 53.8 %
Brown Malt (Crisp) (128.1 EBC) 7.3 %
Maize, Flaked (Thomas Fawcett) (3.9 EBC) 4.9 %
Oats, Flaked (2.0 EBC) 2.2 %
Phoenix [9.25 %] - First Wort 90.0 min 18.8 IBUs
Calcium Chloride (Boil) -
Fuggles [3.20 %] - Boil 60.0 min 5.5 IBUs
Fuggles [3.20 %] - Boil 30.0 min 4.3 IBUs
Invert #3 [Boil] [Boil for 30 min](128.1 EBC) 14.3 %
Invert Sugar #2 [Boil] [Boil for 30 min](65.0 EB 11.2 %
Invert Sugar #4 [Boil] [Boil for 30 min](591.0 E 6.4 %
Milk Sugar (Lactose) [Boil] [Boil for 30 min](0. 0.0 %
Irish Moss (Boil 10.0 mins) -
Yeast Nutrient (Boil 10.0 mins) -
Ringwood Ale (Wyeast Labs #1187) [124.21 ml] -

If anyone's interested in an interesting experiment to assess what invert sugars add to English ales, replace the inverts with Maris Otter and compare. As it stands, this is a very nice little ale. I now use it in small/half batches to culture yeast for a couple brews. Much more fun than pouring spent starter liquid down the drain.

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Re: Strangely low SG reading part way through fermentation

Post by Eric » Sat Dec 12, 2020 8:47 pm

Thanks for that John, never thought to brew a small batch of low gravity beer and simultaneously build a yeast.

I also have "Lets Brew!" and a Lees Mild was the next intended, although not that nor from that book, although it probably did originate from Ron. So a change of plan is in the offing, thank you.
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Re: Strangely low SG reading part way through fermentation

Post by Jase » Thu Dec 17, 2020 5:54 pm

Eric wrote:
Wed Dec 09, 2020 2:29 pm
Jase wrote:
Wed Dec 09, 2020 11:48 am
Hi Guy,
ok, thanks. that makes sense. The Python version is the "Wheelers Wort Works" version, which was re-rwritten in python after Graham Wheeler moved on. It is linked at the top of the forum extras page. It looks like that version doesn't have the refractometer feature....which explains why I couldn't find it...
I should have just downloaded GW's original verision...
Thanks
J
Isn't it still there? I thought it was.

Currently brewing and using a refractometer.
Hi Eric,
So I realise that what you were referring to with the question "Is it still there" was the download link, however what I thought you were asking was whether the menu option was available in the WheelerWortWorks version. Anyway thanks for the detail.

So I did download the original BeerEngine and compared the calculated values with the normal calculator that I use over at brewersfriend. I have a batch of porter just about finished fermenting. The measurements from my refractometer were
SG 12.5B
FG 7B

The calculated gravity readings, compared with an actual hydrometer reading were:

Code: Select all

RF       Wheeler     BrewersFriend   Hydrometer
12.5B    1048        1048
7B       1022        1014            1012
So whilst the Brewersfriend version is a little out, the Wheelers version is a long way from the actual gravity reading from the hydrometer (unless I'm doing something wrong).

Haven't had my hydrometer out for a while so it was nice to get it out again. I'm going to be moving to electronic gravity readings in the new year, so it'll be interesting to compare those with the refractometer calculations and hydrometer readings.

J

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Re: Strangely low SG reading part way through fermentation

Post by Eric » Fri Dec 18, 2020 2:39 pm

Jase wrote:
Thu Dec 17, 2020 5:54 pm

So I did download the original BeerEngine and compared the calculated values with the normal calculator that I use over at brewersfriend. I have a batch of porter just about finished fermenting. The measurements from my refractometer were
SG 12.5B
FG 7B

The calculated gravity readings, compared with an actual hydrometer reading were:

Code: Select all

RF       Wheeler     BrewersFriend   Hydrometer
12.5B    1048        1048
7B       1022        1014            1012
So whilst the Brewersfriend version is a little out, the Wheelers version is a long way from the actual gravity reading from the hydrometer (unless I'm doing something wrong).

Haven't had my hydrometer out for a while so it was nice to get it out again. I'm going to be moving to electronic gravity readings in the new year, so it'll be interesting to compare those with the refractometer calculations and hydrometer readings.

J
Thank you for this, fascinating.

I'd not used a refractometer with any calculator until relatively recent, having found those tried to be too inaccurate for purpose. Only recently did I try Graham's to get a better result that I'd hitherto had and these are Graham's notes that shed some light on the subject.

Refractometer
Beer Engine's refractometer calculator approximates specific gravity from refractometer readings. Approximate is stressed because there is not a direct correlation between hydrometer readings and refractometer readings when measuring brewers' wort and the disparity is even worse once fermentation is under way. There are many contrary issues which make it difficult to use a refractometer accurately for brewing, particularly if trying to relate refractometer readings to specific gravity.

One issue with using refractometers is that different types of sugar have different refractive indices. The refractometers commonly used by home brewers are scaled in degrees Brix, the percentage by weight of sucrose (ordinary household sugar) in solution, but wort is mostly maltose which has a different refractive index and is not equivalent as far as the refractometer is concerned. Indeed, wort contains of a multitude of complex sugars all of which have different and sometimes competing refractive indices. Unlike, say, wine, the sugar balance of a wort is not a fixed, accurately predicable value, but is dependent upon recipe formulation and mashing regime. Thus the values given by refractometers are unreliable in absolute terms in wort, but can give useful relative values if the limitations are understood.

The difference between the refractive index of sucrose and the more complex sugar composition of wort requires that a calibration factor needs to be determined and then applied to correct for the disparity in refractive indices. It is plain that the calibration factor is not a fixed figure, but varies according to wort composition. Different types of beer may require different calibration factors. Also, a hydrometer responds to all dissolved solids, solids such as protein, but the refractometer does not. This implies that different calibration factors may be required at different stages of the brewing process.

Things get rather more complicated during and after fermentation. Apart from the handicap that refractometers are difficult to read in the presence of yeast cells and carbon dioxide bubbles, refractometers are not affected by the presence of alcohol in the same way that hydrometer readings are. Alcohol has a lower specific gravity than water and the hydrometer gives progressively lower readings as alcohol percentage increases. Various assumptions have to be made when using a refractometer during and after fermentation if one is trying to relate Brix to specific gravity. A guesstimate has to be made for the proportion of sugar used for yeast growth and metabolism during the aerobic phase, which does not produce much alcohol, and thereby how much is left for the subsequent anaerobic phase which produces copious amounts of alcohol. The ratio of the sugar consumed during the two phases affects the difference between refractometer and hydrometer equivalent readings. Obviously, the more sugar that is used up for yeast growth, the less will remain to produce alcohol. This ratio of total sugar consumed, to the amount alcohol produced, is affected by yeast pitching rates and dissolved oxygen levels, among other things.

The process of fermentation will also affect the previously-mentioned calibration factor. A typical all-malt wort will contain about 65% maltose and other simple sugars, and 35% more complex sugars that are collectively referred to as dextrins. Prior to fermentation the wort has a particular ratio of sugars and the refractive indices of the various sugars combine to produce a net refractive index for the wort. This requires a specific calibration factor to convert to the equivalent sucrose. During fermentation the maltose is fermented into alcohol, but the dextrins, being mostly non-fermentable, remain. Thus the ratio of maltose to dextrin changes as fermentation progresses, necessitating, in theory at least, a different calibration factor at the low end to that derived for the top end.

Home brewers tend to use the terms Balling, Brix and Plato interchangeably and it is often asserted that they are identical, but they are not the same thing when equated to specific gravity. This is mainly due to the fact that the original Plato and Balling tables were derived at different temperatures. There are also differences between published tables, depending upon source. Americans tend to use Brix, Europeans tend to use Plato. There are differences between official tables of American and European origin. There are errors in the original Balling measurements which find their way into the Brix tables and so into the American official tables. Furthermore, the official American tables use a strange figure for the density of water at 20°C, used in the conversion from density (which is what the Balling and Plato tables actually use) to specific gravity (which is what we are interested in). This again adds to the differences between tables of American origin and those originating elsewhere. In the Beer Engine software there is the conundrum as to whose damn tables does one attempt to match.

However, the differences are sufficiently close for them to be regarded as equivalent as long as they are measured by the same method. A typical 0-32% Brix optical refractometer, for example, can not be read to a resolution of much better than 0.2% Brix, which, when coupled to the accuracy of the instrument (mine is +/- 0.2%), is fairly imprecise and would mask any differences or errors in the Balling or Plato tables. Traditionally, brewers would measure Balling, Brix and Plato using Balling, Brix or Plato hydrometers, not refractometers. Hydrometers do not only measure specific gravity. Hydrometers are available that are scaled in Baume, Brix, Balling, Plato, density or specific gravity. However, like a specific gravity hydrometer, a Brix or Plato hydrometer will give a different reading than a refractometer in the presence of alcohol or dissolved solids. For this reason, in brewing at least, it is wrong to quote Balling, Brix or Plato without specifying how it has been measured because confusion can arise, but the measurement method is rarely quoted in home brewing. One sort of unofficial standard seems to be to use Brix to refer to direct refractometer measurements and Plato for everything else.

Calibration Factor
The primary calibration factor is used to account for the difference in refractive index between ordinary sucrose and the sugars present in wort. It is performed at the original gravity stage, before yeast is added. A measurement is made simultaneously with both a refractometer and a hydrometer. The hydrometer reading is converted to Plato, and then the refractometer reading is divided by the Plato figure derived from the hydrometer. The result is the calibration factor. There is a tool in a pop-up accessed from the refractometer tool in Beer Engine that does the sums for you. Simply enter your hydrometer and refractometer readings in the relevant boxes and the calibration factor is calculated. 1.04 is a typical value, apparently. Hit the save button if you want to save the factor as a default for future use. Without saving, the figure will remain valid only for the current session.

It is frequently stated on the Internet that the calibration factor is 'system dependant' and implies that when you have found the calibration factor for your system you are done and dusted and have no need to worry about it anymore. This strange assertion has, worryingly, found its way into Beer Smith and Promash. It is not system dependant. There is no earthly reason why if you produce a beer to a given recipe on your system, and I produce a beer to the same recipe on my system, that we should get different refractometer readings. It simply does not compute, as Mr Spock used to say. It is, however, recipe dependant. The most obvious illustration is that an all-malt beer will have a different refractive index to a beer with a high level of ordinary sugar in it, and thus would require a different calibration factor.

Using The Refractometer Tool
The refractometer pop-up consists of two panels; 'pre-fermentation measurement' and 'secondary measurements'. The top panel, pre-fermentation measurement, as the name suggests, is for use under circumstances prior to fermentation; mash tun run-off for example or the equivalent of original gravity. It simply adjusts the refractometer reading that is put into the refractometer box by the calibration factor and displays the results in S.G. It can be used stand-alone (without using the second panel). It will also work backwards by putting a number in the original gravity box and it will fill in the refractometer and Brix boxes.

The bottom panel, 'secondary measurements', is for occasions after yeast has been added. It cannot be used stand-alone; the top panel, 'pre-fermentation measurement', must be filled in with the original gravity figure first, because it needs to adjust the reading for alcohol content which can only be determined from original gravity. The bottom panel works in the same way as the top panel; that is, enter the refractometer reading in the appropriative box and the equivalent specific gravity, corrected for both alcohol and calibration factor, is displayed. The calculation will also work backwards by putting a figure into the SG box.
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Re: Strangely low SG reading part way through fermentation

Post by Jase » Fri Dec 18, 2020 4:40 pm

Hi Eric,
Thanks for posting that and I am glad I read it all. So I definitely fall into the camp towards the bottom of the text, thinking that once I had "dialed in" my refractometer, and had my calibration factor, then that is all I needed to use. From that point on, I simply stopped using a hydrometer. However it turns out that simply isn't correct, and the calibration factor needs to be calculated for each batch. I guess that means all my carefully calculated ABV numbers for all my beer over the past few years have possibly been wildly inaccurate. And I've just been through my brew log and my first batch with a refractometer was November 2014! Wow how time flies...

This will prove interesting over the next few months as I start to log the calibration factor for each batch that I brew. I can then see how much variance there actually is. If it only varies from say 1.03-1.05, it won't be too bad, but if we get swings from 1.00 to 1.10 ,then that could be significant. I'm building an iSpindel over the Christmas holidays, so I'll throw that into the mix at the same time when comparing these values, which will also be interesting to see the result of.

J

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