Hi everyone

I've been using BIABacus successfully for a few years now. I've recently been wanting to get more out of my brew days however space and equipement limitations have made it difficult. A Brulosophy experiment looking at full vs partial boil volumes and adding water the to the fermenter prompted me to try brewing a concerntrated wort and splitting it into two beers.

I'm attempting to use BIABacus to do this however when I enter something in section W, water added to fermentor, it adjusts the grain and hop values. I understand the changes in the grain values as this will be a concerntrated wort and therefore efficiency will be lower. What I don't understand is how the efficiency will be lower with hop additions and I'm hoping someone will be able to explain it. My understanding is that using say 50g hops in a full boil would be the same as using 50g of hops in half boil with the other half of the water added later. If anything I would think a half boil would reduce the amount of hops needed due to the lower volume and therefore boil being more vigorous, with a higher evaporation rate and therefore more concerntrated wort.

I've attached the two BIABacus sheets with the only difference being water added to fermenter. Does anyone know the reason for this?

Wow thanks Mally.

I checked this just now by changing the gravity of ambient wort of the full mash to match the partial mash (prior to adding water) and the hop amounts were exactly the same. I never considered hop utilisation reduces the thicker the wort gets... I guess I should've actually studied the tinseth formular...

Based on this I'm considering adding the full amount, or atleast part of the water prior to boil to reduce the amount of hops I'll need so the recipe will be more efficient.