Beer Smith Volume Question

[GPP33]

I thought I had the volumes in Beer Smith figured out then I got thrown for a loop today.

Here's two ways of setting up the volumes...The first has me leaving 0.5gal in the boil kettle and leaving 0.5gal in the fermenter since this is going in my 3 gal keg. The second has me transferring it all to the fermenter and leaving 1 gal in the fermenter. Either way at the end of the boil I have 4 gallons. So why does the IBU calculation change by 20 IBUs and the pre boil gravity change by almost 0.01? I have the same pre boil volume and the same post boil volume. Est OG and FG both stay the same.

Beer Smith 1

• GPP33
• Dec 24, 2018

Beer Smith 2

• GPP33
• Dec 24, 2018

 

[GPP33]

So the second one, putting 0 in for "Trub Loss" under the boil and fermentation section, yielded actual numbers for pre and post boil gravities.

The description for trub loss is "loss of wort due to trub dead space or transfer from boiler to fermenter". I really don't see how this would affect pre boil gravities or IBUs. Is this maybe a bug that was fixed with the latest version of Beer Smith or do I have something incorrect somewhere that's driving this?

 

[Oginme]

You have made two changes in the trub loss without accounting for it in the equipment profile. The first -- trub loss -- is a process loss which affects the volume into the fermenter. The losses in the process also affect the sugars (gravity) and IBU calculations.

The second change, fermenter/bottling loss, does not affect the calculations in the process but the volume you end up with in the bottles.

In your BeerSmith 1 volumes, the numbers do not add up from the end of boil onward. If you end up with 4 gal at the end of boil and lose 0.5 gallon to trub, you cannot have 4 gallons in the fermenter. Your ending volume would need to be 3.5 gallons in the fermenter. This is corrected to balance out the volumes when you changed the loss from the process loss to a fermentation loss.

If you are going to change the target numbers for process volumes out or losses, it is best to do so in the equipment profile so that the program can balance out the volumes properly. By overwriting the values, the program needs to account for a missing 0.5 gal of wort which throws the other related equations off.