Consistently Lower Bottling Volumes

[chrisluki]

Are you saying that the OG into the fermenter is spot on, but it finishes fermenting higher than you are expecting? Wouldn't that suggest you are mashing higher than planned?

Or are you saying that your pre boil gravity is spot on but your gravity in the fermenter is higher? That combined with a lower volume would probably be a higher than predicted boil off.

My pre boil gravity is spot on. When i check my gravity after first stage fermentation (5 days or so), its higher than expected (say only dropping from 1.050 to 1.033), and then when I am bottling it is also higher than expected. This has resulted in my brews being lower in ABV than planned.

I had another thread discussing this, suggesting that my mash temps were too high...which I have since addressed. Buy maybe the fact i was under on my strike and sparge water volumes was also contributing?

Am I making any sense?

 

[seamad]

If your preboil gravity was spot on, was your OG correct as well? if so then your boil off rate is likely correct, just your water volumes are under. You may need to lower your brewhouse efficiency slightly and increase water vol to get both vol and OG correct.
No need to buy a new jug, just weigh out water in increments and mark your vessel, check out this thread if you haven't
http://aussiehomebrewer.com/topic/78701-how-to-add-permanent-volume-markings-to-a-kettle/
FG is not going to be affected if you have the correct starting OG

 

[chrisluki]

If your preboil gravity was spot on, was your OG correct as well? if so then your boil off rate is likely correct, just your water volumes are under. You may need to lower your brewhouse efficiency slightly and increase water vol to get both vol and OG correct.
No need to buy a new jug, just weigh out water in increments and mark your vessel, check out this thread if you haven't
http://aussiehomebrewer.com/topic/78701-how-to-add-permanent-volume-markings-to-a-kettle/
FG is not going to be affected if you have the correct starting OG

Maybe I am not measuring my gravity correctly? I thought OG was preboil gravity? NO???

 

[dblunn]

No, OG is the specific gravity (density) into the FV. Preboil will be lower as the boil off condenses the wort hence the density increases. It makes sense as the OG-FG is used to estimate the alcohol content.
Dave

 

[paulyman]

Maybe I am not measuring my gravity correctly? I thought OG was preboil gravity? NO???

That might be the issue. Measuring pre-boil gravity and volume allows you to determine your mash efficiency. Measuring post boil gravity and volume allows you to determine your boil off. Your post boil should be the same as your OG, you do need to measure the volume into the fermenter though if you want to work out how much you are losing to trub and your brew house efficiency.

 

[chrisluki]

No, OG is the specific gravity (density) into the FV. Preboil will be lower as the boil off condenses the wort hence the density increases. It makes sense as the OG-FG is used to estimate the alcohol content.
Dave

I have been totally f##king things up!!!!

So i boil my wort, chill it with my immersion chiller, transfer to my fermenter and take a hydrometer reading before i pitch my yeast...this is my OG.

My FG reading will be taken BEFORE i transfer to my bottling bucket (Which has my priming solution in it).

ABV is calculated using these two readings...yeah...as opposed to my previous readings of using the preboil gravity.

Every day is a school day!

 

[Nizmoose]

Pre-boil gravity - gravity of wort collected after the mash.

OG - Original gravity, the gravity of the wort just before you pitch your yeast.

FG - final gravity, the gravity of your finished beer after fermentation is complete.




Edit: you could also have a pre-extract / post extract Pre-boil gravity if doing a partial

 

[chrisluki]

Pre-boil gravity - gravity of wort collected after the mash.

OG - Original gravity, the gravity of the wort just before you pitch your yeast.

FG - final gravity, the gravity of your finished beer after fermentation is complete.




Edit: you could also have a pre-extract / post extract Pre-boil gravity if doing a partial

Don't confuse me!!!!

 

[Pogierob]

I think it's fair to say we are getting closer to the issue... Good luck mate.

 

[paulyman]

Eqch brew measure:

1) pre boil gravity and volume
2) post boil gravity and volume
3) volume into the fermentor

Plus, know your temperature accurately.

If you use software like Beersmith and setup a profile for you gear, then it will predict value for each of the measurements above based on 72% brew house efficiency as a default. You can then input your actual values over a number of brews to tune Beersmith to your system. You will quickly see where your results diverge from the predictions and therefore exactly what you have to adjust.

 

[Nizmoose]

Don't confuse me!!!!

Haha yeah sorry, only pay attention to the info above the happy yellow face

 

[chrisluki]

I think it's fair to say we are getting closer to the issue... Good luck mate.

Yeah...I am the issue!!!

 

[chrisluki]

Eqch brew measure:

1) pre boil gravity and volume
2) post boil gravity and volume
3) volume into the fermentor

Plus, know your temperature accurately.

If you use software like Beersmith and setup a profile for you gear, then it will predict value for each of the measurements above based on 72% brew house efficiency as a default. You can then input your actual values over a number of brews to tune Beersmith to your system. You will quickly see where your results diverge from the predictions and therefore exactly what you have to adjust.

I will go home tonight and mark out correct volume measurements on my jugs, and create a measuring stick for my kettle.

THanks for all your help!

 

[Pogierob]

Yeah...I am the issue!!!

this sir is exactly why this forum is here. We all need a little help from time to time and brainstorming with a bunch of people who have likely done something similar is the best way

 

[dblunn]

Every day is a school day!

And the best lessons are learnt this way, all the best for your next brew.
Dave

 

[Truman42]

Where do you live Chrisluki?

I'm sure someone on here would be only to willing to come over and join you during a brew day to show you how to get everything setup properly in beersmith.

 

[chrisluki]

Where do you live Chrisluki?

I'm sure someone on here would be only to willing to come over and join you during a brew day to show you how to get everything setup properly in beersmith.

Im Hobart...not sure how many on here are from my part of the world!

Went home last night and marked out all my jugs and made a measuring stick to use in my kettle...so next time I will be spot on with taking extra measurements.

Hope this will also help me address the lower than expected ABV brews i have been making!! But who knows what ABV they are once they are bottled, cos I have been using the wrong measurements all along!!!