Pre-boil volume is different in apps

[hilljack13]

I have mentioned before I like to use Brewfather and Grainfather apps. For my next planned brew, I noticed the pre-boil volume is .25g higher in the BF app. Both give the same amount of mash and sparge water. Settings are set the same for grain ratio's and losses. I am sure to be missing something, but after staring at the two for good while I can't seem to figure it out. My boil off is 1gal/hr with and I should end up with 5.5g in FV.
So BF shows pre-boil at 7.75g and GF shows 7.50g. Boil time of 90 min with .5gal loss puts me at 5.5 with GF, but high with BF.
Any ideas where I might need to recheck inputs?

 

[DBhomebrew]

Do they both report all volumes corrected for room temp?

 

[hilljack13]

They show wort shrinkage/boil shrinkage, set for 4%. BF specifically says "hot" but GF just asks for the percent. BF also shows sparge temp. I'm not sure would be reported as room temp. I thought this was the wort temp after the boil was over.

 

[DBhomebrew]

BF specifically says "hot" but GF just asks for the percent.

So, BF is reporting the volume hot and GF is adjusting according to the shrinkage %? Your numbers roughly align with that. 7.75*.96=7.45 or 7.5*1.04=7.8

 

[hilljack13]

I really don't know what GF is doing, but what you say makes sense anyway.

 

[DBhomebrew]

To be clear, I'm throwing spaghetti on the wall. I'm not familiar with either software.

 

[hilljack13]

Well, I am still learning too. We'll see after I brew this as to which one I might prefer.

 

[wepeeler]

I had to readjust my total mash volume in BF from what the stock "Foundry 10.5 120V" says for whatever that is worth. It tells me 0.25gal less to start with. I can't figure out why either, but I'm sure it's me, and not the software. You have to brew on your system a few times to figure it out. I was dialed in after 5 brew days.

 

[hilljack13]

I went back and removed the 4% shrinkage from brewfather. It states the volumes are "hot", so like @DBhomebrew said, changing this to 0% gave the amount I was expecting to match Grainfather app. I just need to keep that in mind on how the two differ in their calculations. Sorta makes me wonder if this is partially the cause of the GF sight glass tube to always be about .25 gal off. I know these things aren't exact anyway, but I have noticed that trend.

 

[hotbeer]

Do you check to see if your boil off is consistent from one batch to the next? I wouldn't worry too much about how the software goes about making it's numbers.

You should figure out where each difference in volume or other thing happens in the steps of your brewing process. Then change the things in that section of your software to match your actual results. I'm not going to fuss if different software goes about figuring it differently.

If your actual numbers aren't consistent then your software won't be consistent.

 

[bike2brew]

Make notes, get your result, decide on one software to use as a standard and work from there. I started out by hand calculation of my volumes and compare with the adjusted changes for efficency in my software. This has helped me be consistent brew to brew and predictable w/ a couple points plus or minus. Following advice from friends and reading blogs was both helpful and confusing until I set down w/ paper, pencil, and a hand calculator.

 

[hilljack13]

Do you check to see if your boil off is consistent from one batch to the next?

Everything I have done so far is on from the GF app. I have been off slightly on my fermenter volume. Mostly when I didn't squeeze the life out of the grain when sparging. I have gotten better at hitting my OG too so that is why I haven't done the excess squeezing. I think that change in the app would be the grain absorption ratio?

Following advice from friends and reading blogs was both helpful and confusing until I set down w/ paper, pencil, and a hand calculator.

I started jotting down notes on those kit recipe pages they give ya. Looks like I need to go back and be more detailed. I have only been using what the apps kept.

 

[hotbeer]

I have gotten better at hitting my OG too so that is why I haven't done the excess squeezing.

I don't think squeezing is going to make a difference in SG. But I haven't seen any particular views about that.

Squeezing is something I do if for some reason I don't get the volume I expected.