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Estimated Final Gravity

Sgaura79

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Hello,

      I recently brewed a higher gravity recipe and had a lower brewhouse efficiency than expected. I created a copy of the recipe using the updated brewhouse efficiency for this batch but for some reason the estimated final gravity is different (3.290 Plato for the original and 3.761 for the updated version). How is this the case when both beers have the same fermentables/grain bill and the same yeast/pitch rate?


Thanks,
Sean
 
I would expect, as you probably did, that the recipe with the same grain bill but lower efficiency (and therefore lower OG) would attenuate to a lower FG.  If you export the recipes as .bsmx files and post them, I can look if there is some other explanation for the discrepancy.
 
Hello,

Thank you for the help. I have posted both files.

NEDIPA 1.0 75% BHF
NEDIPA 1.2 70.5% BHF
 
First, you have different batch sizes for the two recipes that you put onto the cloud.  One of the recipes has a batch volume of 206 gal and the other 193.8 gal. 

Next, the recipes do not have the same amount of the ingredients.  As an example, the 70.5 BHE recipe has 161.5 kg (sorry, I work in metric) of Briess Pale ale malt and the 75% BHE recipe has a total of 134.8 kg of the same Pale ale malt.  Each of the other ingredients vary as well.

This leads to the 70.5 BHE recipe having an estimated OG of 1.077/FG of 1.015 and the recipe with the 75% BHE giving you an OG of 1.075/FG of 1.013.

There is a lot more going on than just the change in BHE in the recipes.
 
Hello,

    Here is what I am trying to achieve. I brewed this NEDIPA (original recipe linked below) and my numbers were way off. I'm trying learn my new system and create an accurate profile in Beersmith along with accurate fermentation parameters but I just can't seem to make it work. While I get beer I'm poor with computer software. haha Any insight you could give would be greatly appreciated. Below you will also find my measured perimeters and my current equipment profile. Thank you very much.

beersmithrecipes.com/viewrecipe/2129037/posted-nedipa-09-05-18

Final Mash Temp 150.5 ?
Pre Boil volume 232g
Pre Boil Gravity 16.35 ?P
OG 17.3 ?P
Measured FG (apparent) 2.3?P

Boil Off is consistent around 2.2% with a vigourous boile using a steam condensor




 

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Are you fly sparging or batch sparging?

First thing to do is to, as accurately as possible, track your volumes.  It is much easier to do when batch sparging than fly sparging.  For batch sparging, measure your water input (total water) and pre-boil volume and the difference would be the amount of water left in the grain.  Using this and your grain bill, you can calculate your grain absorption in fluid ounces per ounce of grain.

You seem to have a good lock on your boil off rate, so you are set there.

Next is to measure your post boil volume and volume to the fermenter.  You will need to subtract the thermal expansion value from your post boil volume to correct it to room temperature (which I assume your volume in the fermenter will be).  The difference between this corrected volume and fermenter volume will be your loss to trub and chiller.

Next thing to do is to look at your recipe which you just brewed.  On the 'session' tab, enter in your measured values and the program will calculate your actual mash efficiency and brew house efficiency.  You can use these figures to update your equipment profile along with the measured volumes of your losses.  Your grain absorption can be updated under 'options' > 'advanced'

Now, if you fly sparge the values after the mash remain the same for calculation purposes.  The grain absorption and any mash tun losses become somewhat dependent upon your sparging technique.  Some people calculate and prepare the exact amount of water needed, in which case you can treat it as a batch sparge for purposes of the grain absorption calculation.  If you instead prepare excess water and sparge until you reach your intended volume, the figure for grain absorption really doesn't matter too much, so you should be set with the default value.

If you find you are off in mash temperature, you can make an adjustment in the specific heat or the mash tun weight to tune this in.  Reset the target temperature in your recipe to equal your actual measured temperature, make sure the equipment and grain temperatures reflect your measured values, and now you can edit the equipment profile within the recipe and adjust the mash tun weight or specific heat until the calculated strike temperature matches your actual value.  Save this equipment profile and then click on the disk icon next to the equipment profile to save this new version.  I usually add the date onto the equipment profile name so that I can tell if I have the latest version in the recipe.

You will need to update any other recipes already existing with your new equipment profile.

Now, the estimation of FG is always a questionable calculation.  There are so many variables that contribute to the actual attenuation of the yeast such as: pitching rate, yeast health, fermentability of the wort, grist composition, fermenting temperature, and so forth.  I use the estimated FG value as a guideline.  If you really want to know the ultimate FG of the wort, you can perform a forced fermentation test and see where that takes you for FG.

 
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