View Full Version : Calculating FG from OG to work out when 1/3 Sugar Break is

08-28-2015, 12:26 AM

(I haven't started my recipe yet, I want to make sure i have all the working outs perfect prior to starting and would like some clarification)

I want to do aeration as normal/recommended up to the 1/3 sugar break, my understanding is that you can calculate 1/3 sugar break from (OG-((OG-FG)*.33)).

I've been having trouble finding out how to estimate a FG from the OG, After lot of searching (may i am not the best at searching) i found a place where it said FG=(Gravity-1000)-((Gravity-1000)*Attenuation rate%)+1000

So in my case the Attenuation would be 75% based on the average for my brand of yeast stain.

Based on my recipe the OG calculations should be 1.113

(1133-1000)-((1133-1000)*75%)+1000 = 1033.25 aka 1.033 FG

So the 1/3 sugar break would be (1.113-((1.113-1.033)*0.33)) = 1.086

Is this correct?

08-28-2015, 09:26 AM
You twisted your numbers. Based on my recipe the OG calculations should be 1.113.

Then, in your math you have,,,,(1133-1000)

You will need to know how dry your yeast will go to know how many points you have to divide by 3

08-28-2015, 05:45 PM
Squatchy is right about your number error.

Related to 1/3 sugar break I have a question to add. For step feeding I've read to add 25% of nutrient right after you pitch the yeast, after 48 hrs, after 96 hrs, and last when you reach 30% of the planned value. I'm on my second batch of mead and in both batches my gravity readings were past the 30% of planned value when I checked at 96 hrs. What do you do in that case? I added the nutrients on the 5th day but it's got me wondering what to do for the next batch. I'm thinking to check the gravity every day and add at 48 and 96 hours, but then add again whenever I reach the 30% value regardless if it happens before or after the 96 hour mark. Does that sound about right?

08-28-2015, 08:33 PM
Your touching on something that is always a bit confusing. Here is what I have learned. Every batch has different dynamics based on Yeast, gravity, temps, fruit,spices ect. So because of this, trying to make a one fits all approach isn't really very correct. Especially when your using hours and days. You could possibly cut your ferment time in half buy raising the temps. Or you could stretch it out by fermenting in the fridge or a colder controlled environment. On top of that different manufactures make their products with different values. Most won't even tell your quantities of this or that. And another thing is you have to be able to respond in a fluid fashion. If it starts to stink it's telling you to do something. And scientist say they can't process DAP after a certain point either. Higher OG require more nutrients than lower OG. Melomels have natural nutrients on board because of the fruit additions. Darker honeys have more than lighter honeys.

I have run out of time right now. Iwill come back to add more. The above is, in some degree, part of the confusion. Hydrometer readings are more consistent, batch to batch than any other

08-28-2015, 10:37 PM
I totally agree and have been thinking that as I've been going through my first few batches. I was wondering how an author can assign a fixed value (time) to any particular batch given all the variables. So far my two batches of mead and three batches of wine have fermented down to 1.00 or less inside a week. I attribute some of this to the ambient temp in my house here in Phoenix, AZ which I keep at 76 which is a little on the warm side for a lot of yeasts. So for the next batch I'm thinking to add nutrient at yeast pitching, at 24 hrs, again at 48 hrs, and then check the 30% point which should be around 60 hrs - that's my edumacated case anyway. I agree though, you have to plan and adjust the rules of thumb for your particular batch.

08-28-2015, 11:24 PM
I think what we all end up having to do is embrace a certain protocol and then personalize it based on our own experience. Lallemand list the nitrogen needs of their yeast. That is a start. And Fermaid K, Dap and Fermaid-O list their nitrogen values. I have read the yeast can not use Dap after the half way mark. Oskaar likes to use Dap early to get a supercharged start. Bray like to feed the last meal at the 2/3 sugar break. I think lots of guys wait to feed the first meal until the lag phase is over so your not feeding wild competitors before your yeast takes hold. Maybe tomorrow I can get more specific. I'm having a very hard time physically staying upright for very long time and I've maxed out again trying to write just this short post

08-29-2015, 05:14 PM
I hope you feel better there Squatchy. I appreciate all the info you pass along.

08-30-2015, 02:39 PM
Thanks for the kind words EJ. The bottom three verrtibrea in my lumbar region have fused together on thier own. I have had a bought of sciatica so badly that I haven't been able to even sit up in a chair or bed. If you do a search on here for TOSNA you will find a protocol using Fermaid O. The last 2 batches that I have made was with this method and it tasted very good and very early on it became drinkable. After learning from Oskaar I am now going to dose some Dap only in the first addition along with the Fermaid O and then finish up with straight Fermaid O. I will give you additional traditional feeding protocol using Dap and Fermaid K later today.

08-30-2015, 10:32 PM
This is my approach (and although there are similarities to other nutrient methodologies, we do differ somewhat). It agrees for the most part with the recommendations of Lallemand and other commercial yeast manufacturers.

First, I make an assumption that the honey that I use in any of my musts provides negligible amounts of YAN.

Next, I determine what (if any) fruit I will use in primary fermentation.

Then, I try to find out (for melomels) how much YAN is present in the fruit I plan to use (measured in ppm, for the given volume of fruit I'll add in primary). If I can't find info on YAN for my particular fruit, I assume a baseline value of 100 ppm. That's close enough for gov't (and mead) work.

Then I work out the dilution of that fruit-supplied YAN in my total volume of must. If for example I am mixing up a 5 gallon batch of must, and one gallon is pure fruit at 100 ppm, then I will dilute by a ratio of 1/5, so the net YAN in my fully mixed must is 100 * 1/5, or 20 ppm.

I next find the nitrogen requirements of my yeast. For most commercial yeast strains we only know if the demand is low, medium or high. For low demand yeasts, I ensure that the total YAN is 225 ppm. For medium demand yeasts, I ensure that the total YAN is 300 ppm. For high demand yeasts, I ensure that the total YAN is 350 ppm. These are numbers that I've found through trial and (mostly) error that will produce clean ferments with minimal H2S production in my meads.

Note: Those values are what I use for "normal strength" meads, which for me are musts that range in initial gravity from 1.080 to 1.100 (Initial Brix range of 20 to 24). For initial Brix of 24 to 27 (SG from 1.101 to 1.115) I multiply my normal strength numbers by 1.1. For Brix from 27 to 32 (SG from 1.116 to 1.140) I multiply the normal strength numbers by 1.25. For initial gravities in excess of that, I wing it.

I calculate how much Fermaid-K and DAP to use knowing that Fermaid-K has 13% YAN by weight and DAP is 21% YAN by weight. Another way to express the YAN content of those is that 1 gram of Fermaid-K provides 130 ppm of YAN to a single liter of must, and 1 gram of DAP provides 210 ppm of YAN to a liter of must.

08-30-2015, 10:35 PM
How to Calculate Nutrient Additions Using Fermaid-O
The amount of required nutrient additions are based on your starting gravity. For an easier calculation convert to Brix and figure out your target mg of Nitrogen per liter using the following as a starting point:

21Bx = 200 mg N/L
23Bx = 250 mg N/L
25Bx = 300 mg N/L
27Bx = 350 mg N/L

1g/gal of Fermaid-O = 50ppm N/L (effectiveness)
(1g = roughly .25 tsp)

In a 5 gallon batch of 1.115 SG (27Bx)
Target = 350 mg N/L
Equates to 7g/gal (350 mg / 5 gals)
35g of total Fermaid-O to be used in this 5 gallon batch

08-30-2015, 10:36 PM
Here for US metrics
I've been using 25 ppm and 50 ppm for Fermaid K and DAP (respectively) in 1 g/gallon doses. Slightly off, but the round numbers are nice.