Beersmith volume and OG

TheWoods · Jan 13, 2015

Hello Guys,

I am a bit confuse about volume calculation and gravity in the beersmith software. When I change my equipment profile for the same recipe, the OG change even if I don't change the pre-boil and post boil volume.

Lets say I have 55L pre-boil and 48L post-boil and 3L loss to trub, shrinkage 2L and batch size 43L Beersmith call the OG at 1.073. Because I I made a DIPA and I decided to leave around 8L in the kettle because of the trub I tried to change the equipment for this recipe as follow. 55L Preboil, 48L post-boil (as this as not changed), 8L trub, shrinkage 2L and batch size at 38L (because this is what I collected in the fermenter) Beersmith called for an OG of 1.083.

The same mash and the same volume pre-boil and post-boil shouldn't have changed the OG? The 8L left in the kettle is suppose to be the same gravity as what I collected?

Thanks for you help on this!!

LLBeanJ · Jan 13, 2015

Not sitting in front of BS right now, so can't play around with your scenario, but off the top of my head, the only things that would change OG would be: fermentables, volumes, & estimated efficiency. Sounds like the first two have not changed (double check your grain bill has not changed, just to be sure).

Did you make any changes to the recipe's estimated efficiency?
What about boil length or boil-off rate, as these both affect volumes?

TheWoods · Jan 13, 2015

Grain bill did not change and my tot efficiency did not change. The estimate mash efficiency which is the box at the right of the tot efficiency did change thought.

I wonder if the fact that I put 8L trub instead of 3L trub my tot efficiency should be less because I collected less beer at the end.

I f I try to match the numbers:

tot efficiency 78% with 3L trub ------> est mash eff: 84%
tot efficiency 70% with 8L trub ------> est mash eff: 84.7%

Which is my measured mash eff at 84.4%

Looks like the Bottling volume as a lot to do with tot efficiency?

I will need to change my tot efficiency each time I will have a small trub or big trub?

LLBeanJ · Jan 13, 2015

TheWoods said:
Looks like the Bottling volume as a lot to do with tot efficiency?

I will need to change my tot efficiency each time I will have a small trub or big trub?

Deleted - the info I gave was inaccurate. Oginme's post directly below is a better answer.

Oginme · Jan 13, 2015

BeerSmith cues its calculations based upon 'Brewhouse Efficiency' which is efficiency into the fermenter. If you change the trub loss, BS will adjust your mash efficiency to keep your brewhouse efficiency at the target number. I've noted to Brad, that for most of us, the mash efficiency is fairly consistent and the brewhouse efficiency (as he has defined it) changes quite a bit depending upon recipe trub amounts, etc. We will see if he makes that a change with the updates, but I am not depending upon it.

So, in addressing your problem, I would note your average mash efficiency and adjust the brewhouse efficiency with the increased trub amount to get the mash efficiency in line with your standard results.