Brew Day Numbers Oddity/Oddities

[DaveCS]

Hey all,

This is the third time this has happened to me. I'm coming up short!! I'm using Brewer's Friend to create recipes and I wonder if "they" are incorrect in their OG numbers.. hmmm...

I'm hitting my volumes and my pre-boil gravity but, post boil, I'm losing points. Today I should have had 1.052 and ended at 1.048 for a brown ale I created - I'm not overly worried about this batch per se but missing the post boil numbers when I hit my pre-boil numbers concerns me.

The Volume to the fermenter is what I wanted (2.5 Gallon) so I know my water calculations are correct... hmmm.. where am I going wrong?

Any and all input is welcome

ETA: I do BIAB so please take that into account

Cheers,
Dave

 

[RPh_Guy]

How are you measuring your volume? What is the temperature when you measure it? Have you calibrated your measuring instrument?

Did you calibrate your hydrometer (or refractometer)?

Are you adjusting the hydrometer reading for temperature or cooling the sample?

Just based on what you've said, it's possible you might not be accounting for thermal expansion.
I use brewer's friend but don't measure my pre-boil gravity. I typically hit predicted numbers, or can explain why I didn't.

 

[muledogus]

Some variance in BF's calculation for evaporation and your system's actual evaporation maybe? Are you getting a nice rolling boil? I don't use BF so I can't get into too much detail but are you sure your estimated boil size and boil time are correct on there?

 

[GPP33]

I also don’t use BF but Beer Smith has a bunch of volumes that all need to be entered correctly in order for the calculations to work. Even still pre boil gravity is hit and miss while post boil gravity is pretty consistent. I wouldn’t worry about 4 points, you won’t notice it.

 

[Smellyglove]

You have a measurment error, somewhere. I'd doublecheck the instrument you use for gracity-readings. And also make sure you use it at the temperature it's meant to be used at. And also doublecheck that your volumes are correct. And take into account at what temperatures you check your gravities. Things are happening the way they are, you just need to make sure you are measuring and understanding the measurments correctly.

 

[DaveCS]

Thanks for your replies all. I'm still mulling this over.

To address the questions:
1) Measuring my volume via a stainless steel ruler in the midst of the wort (standard formulae)
2) Temperature measured (post boil) is after cooling (not prior) so taken just before I pitch my yeast
3) Not going to "calibrate" my ruler (but I get the question...)
4) Hydrometer is calibrated to 60F - I took this into account in my readings
5) I've taken into account temps that I've taken the gravity readings at

Honestly.. after looking at it again I think, and this is just my theory, BF is calculating based on the malts listed in their DB. For example... today I used Simpsons Dark Crystal which was 1 ppg more than the Crystal 80 listed in BF. I also noted that Pale Chocolate I used was 2 ppg more than than the pale chocolate BF had listed. I honestly think some of BFs numbers are off.

Put it this way, I also used Priceless' biab calculator and it stated I should have had 1.044 as a post boil gravity... so go figure...

Cheers,
Dave

 

[Smellyglove]

Thanks for your replies all. I'm still mulling this over.

To address the questions:
1) Measuring my volume via a stainless steel ruler in the midst of the wort (standard formulae)
2) Temperature measured (post boil) is after cooling (not prior) so taken just before I pitch my yeast
3) Not going to "calibrate" my ruler (but I get the question...)
4) Hydrometer is calibrated to 60F - I took this into account in my readings
5) I've taken into account temps that I've taken the gravity readings at

Honestly.. after looking at it again I think, and this is just my theory, BF is calculating based on the malts listed in their DB. For example... today I used Simpsons Dark Crystal which was 1 ppg more than the Crystal 80 listed in BF. I also noted that Pale Chocolate I used was 2 ppg more than than the pale chocolate BF had listed. I honestly think some of BFs numbers are off.

Put it this way, I also used Priceless' biab calculator and it stated I should have had 1.044 as a post boil gravity... so go figure...

Cheers,
Dave

You hit your preboil gravity as you stated earlier.. So the PPG's shouldn't matter. Unless you measured incorrectly..

It seems like it's between post-mash and post-boil where you have some error, again, if you measured correct.

What do you mean with "I took this into account in my reading" when it comes to hydrometer temperature calibrating? Did you measure at that temperature? If not, than the reading is not valid if it the offset between the reading and the stated temp for your hydrometer was "big enough".

 

[DaveCS]

What I mean is, with respect to the hydrometer reading, is that, again just according to BF, when I get a reading of 1.028 at 107.4 F it translates to 1.035 at 60 F (what my hydrometer is calibrated to) - and based on the info via BF via calculations for Pre-Boil Gravity, I should be at 1.036.. I can live with a loss of 1 point.

I'm racking my brain trying to figure out where the error is... which is obviously there.. I just can't see it.

 

[Smellyglove]

What I mean is, with respect to the hydrometer reading, is that, again just according to BF, when I get a reading of 1.028 at 107.4 F it translates to 1.035 at 60 F (what my hydrometer is calibrated to) - and based on the info via BF via calculations for Pre-Boil Gravity, I should be at 1.036.. I can live with a loss of 1 point.

I'm racking my brain trying to figure out where the error is... which is obviously there.. I just can't see it.

Right. I'd call that reading unvalid. When I said "And also make sure you use it at the temperature it's meant to be used at" I mean it. You are not being precise in your measurements. You are getting your info by a proxy, which is the calculator. So to be honest I'd call it at best a very open ballpark reading, unless you cool a similar sample down, and confirm/check it against a hot sample. It is a shortcut, which can end up skewed. Measuring hot samples usually gives you a higher reading.

 

[DaveCS]

Clearly I'm incorrect in everything I've been doing.. My apologies for even thinking I should post such a thing here.

Cheers and thanks,
Dave

 

[Smellyglove]

Clearly I'm incorrect in everything I've been doing.. My apologies for even thinking I should post such a thing here.

Cheers and thanks,
Dave

I just said that the sample was not at the correct temperature which may give you wrong numbers. If you don't want to accept the help given to you regarding your issue it up to you. But if you don't look into it you have nothing to complain about, except for your readings which are not where they should be if you have the boiloff dialed in.

 

[DaveCS]

You're right.. I am wrong.

Cheers,
Dave

 

[ancientmariner52]

Clearly I'm incorrect in everything I've been doing.. My apologies for even thinking I should post such a thing here.

Cheers and thanks,
Dave

C'mon, Dave. Don't be like that. Smelly is trying to help you out. I'm not a scientist like a lot of members here, but taking a hot hydrometer sample and depending on a correction factor really isn't good practice. Please try the suggested methods before you dismiss them. Together we can figure out what's going wrong.

 

[DaveCS]

C'mon, Dave. Don't be like that. Smelly is trying to help you out. I'm not a scientist like a lot of members here, but taking a hot hydrometer sample and depending on a correction factor really isn't good practice. Please try the suggested methods before you dismiss them. Together we can figure out what's going wrong.

I can get behind that.
I'll try that next brew day. I'll wait till the sample cools to 60F to see what the reading is.

Cheers,
Dave