• Please visit and share your knowledge at our sister communities:
  • If you have not, please join our official Homebrewing Facebook Group!

    Homebrewing Facebook Group

Weighing your BOMM

Homebrew Talk

Help Support Homebrew Talk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Last edited:
I'm guessing that weighing may also be a good way to judge when fermentation has completed. I assume no change in weight should mean fermentation has stopped? Again, much easier than taking gravity readings.
 
I posted this on another thread, but I'll post it here also because it shows the 17 bottles of mead (plus 2 more that will join them) that I've been managing using the weighing method as opposed to taking direct gravity readings.
Yeast_Test_Phase1.jpg


You can see where I wrote the original weight on each of the bottles as well as the weight's that I computed for the first and second sugar breaks.

For these 3L bottles, I use a scale with 0.1g resolution and is repeatable, so I think that may be useful in deciding when fermentation has finished. i.e. if the weight seems pinned at a particular number for long enough, then I'm theorizing that means fermentation is completed.
 
Last edited:
I don't have a scale that'll weigh 60 pounds ;)
How about 100-lbs capacity postal scale? Or if your not as worried about the resolution, a digital bath scale that reads out in lbs and kg, +/- 0.2lbs/0.1kg can be had for under $20.
 
Today I started a new traditional mead using 71B in a 1 gallon jar. I have instrumented it with a TILT wireless hydrometer so that we can finally compare SG readings to weight lost and see how good our calculations have been. I weighed the honey that went into it to the nearest gram, and I weighed the entire jar, TILT included, to get a starting weight measurement. OG, as reported by TILT, is right on the money at 1.105 SG. I have two rounds of nutrient additions at the first and second sugar break that have yet to be done, so I'll measure the impact of those on weight also. I'll keep track of the weight measurements when I perform them and time and date stamp them so that they can later be compared with the TILT's SG measurements at the same time. At some point I'll post the data so that everyone can make their own comparisons if they want to and draw their own conclusions about how accurate (or not) this weighing method actually is.

:cool:

@renrutle: where is Magnolia located? When I click on your locator, it gives a BestBuy store in Austin, Texas.
 
Last edited:
Today I started a new traditional mead using 71B in a 1 gallon jar. I have instrumented it with a TILT wireless hydrometer so that we can finally compare SG readings to weight lost and see how good our calculations have been. I weighed the honey that went into it to the nearest gram, and I weighed the entire jar, TILT included, to get a starting weight measurement. OG, as reported by TILT, is right on the money at 1.105 SG. I have two rounds of nutrient additions at the first and second sugar break that have yet to be done, so I'll measure the impact of those on weight also. I'll keep track of the weight measurements when I perform them and time and date stamp them so that they can later be compared with the TILT's SG measurements at the same time. At some point I'll post the data so that everyone can make their own comparisons if they want to and draw their own conclusions about how accurate (or not) this weighing method actually is.

:cool:

@renrutle: where is Magnolia located? When I click on your locator, it gives a BestBuy store in Austin, Texas.
Very good, keep us posted!
 
After a bit of a delay I got 3 batches started this last Saturday (3-16) and have some data to report.
I am taking both a weight and a SG reading. I hope to have some graphs soon and will post a link to the google doc once it is ready. All three have ~2.3# of honey and started at an OG of a bit over 1090. All weights below are in grams.

So far the ratio of Δ weight to Δ SG is running between 4.6 and 3.3 with an overall average of 3.7.


BOMM 1

Wt Honey 1074
Wt Total 5305
Day # - Wt g - SG
Day 1 - 5305 - 1094
Day 2 - 5299 - 1092
Day 3 - 5275 - 1086
Day 4 - 5250 - 1079
Day 5 - 5225 - 1072
Day 6
Day 7


BOMM 2

Wt Honey 1102
Wt Total 5400
Day # - Wt g - SG
Day 1 - 5400 - 1092
Day 2 - 5399 - 1090
Day 3 - 5376 - 1085
Day 4 - 5352 - 1079
Day 5 - 5328 - 1073
Day 6
Day 7


BOMM 3

Wt Honey 1080
Wt Total 5384
Day # - Wt g - SG
Day 1 - 5384 - 1092
Day 2 - 5376 - 1089
Day 3 - 5554 - 1084
Day 4 - 5330 - 1078
Day 5 - 5307 - 1071
Day 6
Day 7

Edit:
All additional notes will be published here.
https://docs.google.com/spreadsheets/d/1HO9oETsDfIBzg3mDongO-Axkk5r4g5PK7ZwKrVTFe90/edit?usp=sharing
 
Last edited:
Today I started a new traditional mead using 71B in a 1 gallon jar. I have instrumented it with a TILT wireless hydrometer so that we can finally compare SG readings to weight lost and see how good our calculations have been. I weighed the honey that went into it to the nearest gram, and I weighed the entire jar, TILT included, to get a starting weight measurement. OG, as reported by TILT, is right on the money at 1.105 SG. I have two rounds of nutrient additions at the first and second sugar break that have yet to be done, so I'll measure the impact of those on weight also. I'll keep track of the weight measurements when I perform them and time and date stamp them so that they can later be compared with the TILT's SG measurements at the same time. At some point I'll post the data so that everyone can make their own comparisons if they want to and draw their own conclusions about how accurate (or not) this weighing method actually is.

:cool:

@renrutle: where is Magnolia located? When I click on your locator, it gives a BestBuy store in Austin, Texas.

Thanks for running your trials. I'm using the turkey baster method to fill the hydrometer tube for taking measurements.

Magnolia is about 50 NW of Houston on 249. The link works for me. :D
 
After a bit of a delay I got 3 batches started this last Saturday (3-16) and have some data to report.
I am taking both a weight and a SG reading. I hope to have some graphs soon and will post a link to the google doc once it is ready. All three have ~2.3# of honey and started at an OG of a bit over 1090. All weights below are in grams.

So far the ratio of Δ weight to Δ SG is running between 4.6 and 3.3 with an overall average of 3.7.


BOMM 1

Wt Honey 1074
Wt Total 5305
Day # - Wt g - SG
Day 1 - 5305 - 1094
Day 2 - 5299 - 1092
Day 3 - 5275 - 1086
Day 4 - 5250 - 1079
Day 5 - 5225 - 1072
Day 6
Day 7


BOMM 2

Wt Honey 1102
Wt Total 5400
Day # - Wt g - SG
Day 1 - 5400 - 1092
Day 2 - 5399 - 1090
Day 3 - 5376 - 1085
Day 4 - 5352 - 1079
Day 5 - 5328 - 1073
Day 6
Day 7


BOMM 3

Wt Honey 1080
Wt Total 5384
Day # - Wt g - SG
Day 1 - 5384 - 1092
Day 2 - 5376 - 1089
Day 3 - 5554 - 1084
Day 4 - 5330 - 1078
Day 5 - 5307 - 1071
Day 6
Day 7

Are they each one gallon in fluid volume? Which yeast? What temperature? Which nutrient protocol? What water did you use?

I'm guessing you're using 1388 as the yeast, given that it's BOMM, but it doesn't hurt to be sure.

Thanks for posting your data, and I'm looking forward to your graphs!
 
Last edited:
I recently started 71B and Fresco trials, with starting OG's either at or near 1.105, and each monitored with a TILT. For 71B, you can view the real-time progress here:https://docs.google.com/spreadsheets/d/1WGbJzJ4C78lqVa2D678XE5Rov4gVgeAeJFAfthuz-Pw/edit?usp=sharing

and for Fresco here:https://docs.google.com/spreadsheets/d/1UameIZ6ks_67gMgiSO9XC1P1eYEtDXUQTnHbteS1s2o/edit?usp=sharing

Here's my dataset in CSV format:
Honey(g),Net(g),SG
1049,3524,1.105
1049,3475,1.085
1049,3448,1.078
1049,3424,1.071
1049,3416,1.068
1049,3414,1.067
1049,3411,1.067
1049,3403,1.065
1049,3394,1.062
1049,3379,1.058
1049,3357,1.054
1049,3341,1.048
1049,3313,1.041
1049,3286,1.031
1042,3503,1.103
1042,3488,1.097
1042,3463,1.09
1042,3452,1.087
1042,3450,1.086
1042,3438,1.082
1042,3426,1.078
1042,3404,1.071
1042,3368,1.061
1042,3343,1.053
1042,3303,1.04
1042,3265,1.027

With the data now collected, the next step will be to do a regression analysis to come up with a predictive equation. i.e. given the weight of the honey used initially and given the weight of the water+honey solution, predict the SG that would correspond to that. I may have to represent the data differently than that, but I'll see if that works.

I plan to use either Excel or Libra Calc to crunch the numbers.
 
Last edited:
Are they each one gallon in fluid volume? Which yeast? What temperature? Which nutrient protocol? What water did you use?

I'm guessing you're using 1388 as the yeast, given that it's BOMM, but it doesn't hurt to be sure.

Thanks for posting your data, and I'm looking forward to your graphs!

They are all in gallon glass carboys with orange blossom honey. Using WLP570 though in these three batches. Once my batch with 1388 finishes in a week or so I will re-pitch that in two or three more 1 gallon batches. Counter temp is running steady at 68F. I'm following the 1/3, 2/3 schedule on the calculated SG readings for nutrient additions. I'm on a well so it is all well water; about 50% through the RO filter and the rest straight from the tap.
 
I recently started 71B and Fresco trials, with starting OG's either at or near 1.105, and each monitored with a TILT. For 71B, you can view the real-time progress here:https://docs.google.com/spreadsheets/d/1WGbJzJ4C78lqVa2D678XE5Rov4gVgeAeJFAfthuz-Pw/edit?usp=sharing

and for Fresco here:https://docs.google.com/spreadsheets/d/1UameIZ6ks_67gMgiSO9XC1P1eYEtDXUQTnHbteS1s2o/edit?usp=sharing

With the data now collected, the next step will be to do a regression analysis to come up with a predictive equation. i.e. given the weight of the honey used initially and given the weight of the water+honey solution, predict the SG that would correspond to that. I may have to represent the data differently than that, but I'll see if that works.

I plan to use either Excel or Libra Calc to crunch the numbers.


I hope you don't mind but I added your data to my spreadsheet. Ignore the stuff below the charts on the first tab. those are random notes and calculation to try and make sense of the data.

https://docs.google.com/spreadsheets/d/1HO9oETsDfIBzg3mDongO-Axkk5r4g5PK7ZwKrVTFe90/edit?usp=sharing


Mine are about a week behind yours. I am also planning to run a batch with orange blossom and RedStar Premier Blanc yeast and a parallel one with just sucrose at the same OG. I'm thinking that sucrose should give a baseline and the Premier Blanc should have no problem consuming all the sugar to arrive at a total weight loss.

When did you make your nutrient additions?

I'm thinking that this may be as simple as multiplying the honey weight by some factor (possibly involving on the starting gravity) to arrive at the weight loss that corresponds to the 1/3 and 2/3 SG readings. Wishful thinking at this point in the data collection process.
 
I hope you don't mind but I added your data to my spreadsheet. Ignore the stuff below the charts on the first tab. those are random notes and calculation to try and make sense of the data.

https://docs.google.com/spreadsheets/d/1HO9oETsDfIBzg3mDongO-Axkk5r4g5PK7ZwKrVTFe90/edit?usp=sharing


Mine are about a week behind yours. I am also planning to run a batch with orange blossom and RedStar Premier Blanc yeast and a parallel one with just sucrose at the same OG. I'm thinking that sucrose should give a baseline and the Premier Blanc should have no problem consuming all the sugar to arrive at a total weight loss.

When did you make your nutrient additions?

I'm thinking that this may be as simple as multiplying the honey weight by some factor (possibly involving on the starting gravity) to arrive at the weight loss that corresponds to the 1/3 and 2/3 SG readings. Wishful thinking at this point in the data collection process.

I don't mind at all. That's why I posted the dataset: so that anyone can use it however they want.

I used the 6b protocol for BOMM that's on Bray's website: https://denardbrewing.com/blog/post/brays-one-month-mead/
So, to answer your question, I do the nutrient additions 1/3 up-front, 1/3 at the first sugar break, and then 1/3 at the second sugar break. On this first pass I didn't account for the extra weight of the nutrient additions at the first and second sugar breaks, but it's probably not significant anyway.

Therefore, there are really only two SG's that I need to predict based on the amount of weight lost: the first sugar break and the second sugar break. Like you, I've hopeful that the math will be a simple linear relationship in that area of interest.

I don't really need to know the SG for when fermentation halts. All I need to know is when the weight stops changing, because I'm assuming that is the indicator for when fermentation is finished.
 
Last edited:
I didn't account for the extra weight of the nutrient additions at the first and second sugar breaks, but it's probably not significant anyway.

I guess I'm using his 6a protocol. I haven't bought any Fermaid O. 1/4 tsp DAP and 1/2 tsp Fermaid K weigh in at 4-5 grams. 0.4 tsp of Fermaid O is probably 3-4 grams. I do add nutrients and 1/4 tsp potassium bicarbonate at the start.
 
I plotted the SG vs weight lost for the first part of my dataset, which is for yeast 71B that had OG 1.105:

71B_dataset.png


It's almost linear, but not quite.

Given the OG at 1.105, the first sugar break would be at 1.070 SG, and the second at 1.035 SG.

Although I didn't capture weight measurements at exactly those SG points, interpolating the data suggests that the weight lost corresponding to 1.070 SG was 103g, and the weight lost corresponding to 1.035 SG was 223g. i.e. The weight lost at the second sugar break was more than twice the amount lost at the first sugar break. I'm not sure what accounts for that.

When I find time I'll run the numbers for the Fresco yeast, which was the other half of the dataset, and which had an OG of 1.103, and see how that compares.

I think in the future that continuously capturing the weight data using the arduino scale, which could time and date stamp all the entries, will prove useful, because then I'd have the exact weight lost that corresponds to the exact SG as measured by the TILT. i.e. no interpolation error, but the spot on weight lost for any SG of interest.
 
Here's the graph for the Fresco yeast dataset:

Fresco_dataset.png


It's the same sort of thing: there's a slight bend that happens in the middle that keeps it from being a straight line. So it too will have more than double the weight lost by the second sugar break as by the first sugar break.
 
Anyhow, until the anomaly is explained, a simple formula that appears to match the data fairly closely for the first sugar break is just:

First sugar break: (grams of honey)/10

To be conservative, just double that number to get the grams of weight loss for the second sugar break. i.e.

Second sugar break: (grams of honey)/5

Of course, one can crank out more precise numbers, but these are easy to remember and work with.
 
Is the x axis the weight?

And I need to point out that temperature will have a direct impact on the rate of change.
I'm also surprised that it seems to be such a linear function. I would have expected some 2nd order behavior as the ferment nears completion.
 
Last edited:
Is the x axis the weight?

And I need to point out that temperature will have a direct impact on the rate of change.
I'm also surprised that it seems to be such a linear function. I would have expected some 2nd order behavior as the ferment nears completion.

X-axis is amount of weight lost, as compared to the starting weight, measured in grams. Verticle axis is the SG, as measured by the TILT. There's no time component here, so no rate of change can be inferred from this plot. You can, however, see the rate of change from the TILT plot on the link I have provided.

Actually, I was expecting that it would be perfectly linear, except maybe a little off toward the beginning as the solution becomes saturated with CO2 that doesn't get immediately released. The OP calculated that might be as much as 7g per gallon. I may try measuring that experimentally when I get my vacuum chamber hooked up. Aside from that, I'm honestly surprised that the plot appears to have a slight bend in the middle (which is what I'm referring to as "the anomaly") rather than being a straight line through all the points past the beginning (since temperature is pretty stable, as can be seen in the TILT plot).

Looks as though with both yeasts the bend happens around the same place, right around 1.05-1.07SG. Maybe some kind of change in metabolism happens at that point that's not purely just the sugar metabolism into CO2 and alcohol that we've been modelling? I mean maybe it's around that point where the yeast switches from digesting glucose into digesting more complex sugars like sucrose/fructose, and that somehow affects the SG a little differently? I have no clue, but that's my wild guess. I have read, though, that yeast is preferential that way in the order in which it digests sugars (least complex first and more complex last).
 
Last edited:
Well, interestingly, looking at the TILT curve (which anyone reading this can also do by clicking on the links I had provided above), with both yeasts there's a curve inflection in the same 1.05-1.07SG range. So, I do think something physical is going on there, and it's not just some artifact of the data gathering.
 
I hope you don't mind but I added your data to my spreadsheet. Ignore the stuff below the charts on the first tab. those are random notes and calculation to try and make sense of the data.

https://docs.google.com/spreadsheets/d/1HO9oETsDfIBzg3mDongO-Axkk5r4g5PK7ZwKrVTFe90/edit?usp=sharing


Mine are about a week behind yours. I am also planning to run a batch with orange blossom and RedStar Premier Blanc yeast and a parallel one with just sucrose at the same OG. I'm thinking that sucrose should give a baseline and the Premier Blanc should have no problem consuming all the sugar to arrive at a total weight loss.

When did you make your nutrient additions?

I'm thinking that this may be as simple as multiplying the honey weight by some factor (possibly involving on the starting gravity) to arrive at the weight loss that corresponds to the 1/3 and 2/3 SG readings. Wishful thinking at this point in the data collection process.
Looking forward to seeing how your data evolves and whether it exhibits a similar "shift" part way through the fermentation. I previously thought you had started on February 20 (as shown in your OP post), but I guess you were measuring only weight and not SG back then.

Looks as though the [total honey weight/10] rule fits pretty well for the first sugar break on one of your ferments and is a little premature on the other. I figure, though, to be conservative it's better to error on the side of adding a little too early than too late. :yes: That said, I hope you find a better formula than me.
 
Last edited:
Looks as though the [total honey weight/10] rule fits pretty well for the first sugar break on one of your ferments and is a little premature on the other. I figure, though, to be conservative it's better to error on the side of adding a little too early than too late. :yes: That said, I hope you find a better formula than me.

Anyhow, until the anomaly is explained, a simple formula that appears to match the data fairly closely for the first sugar break is just:

First sugar break: (grams of honey)/10

To be conservative, just double that number to get the grams of weight loss for the second sugar break. i.e.

Second sugar break: (grams of honey)/5

Of course, one can crank out more precise numbers, but these are easy to remember and work with.


My data seems to be tracking closely with yours.
First break is at:
Δ weight/ Honey Weight = ~10%

I have another day or so to reach the second break but it looks like it will be close to the ~20% weight loss you noted.

To be clear, this weight loss is 10% and 20% of the weight of the honey not the total weight of the fermenter.
 
Yesterday I started a smaller batch at OG 1.103 using just 860g honey and QA23 yeast. When there's enough data I'll post it. That way we'll see if the same formula scales to a smaller batch or whether it's particular to the 1 gallon batch size we've both been teting so far. I expect it will still hold true, but we shall see.
 

Latest posts

Back
Top