Water Volume Help Please

[hellesyeah]

I have done three BIABs now and am having a consistent problem with too much water. The simple approach is to use less water, but I am trying to get a better handle on that.

I use Beer Smith which told me the water to start with.

My target is 5.5G into fermenter since I know I'll have about 2 quarts of yeast slurry left behind so this number seem predictable. I harvested this yeast slurry so that number is accurate.

I keg into 5G soda kegs.

Last brew: BIAB as stated with a Wilser bag in a 15G kettle starting with 7.5 G of strike water. 10# grain bill and 2 ounce hop bill as this was a German styled Pilsner. After mash I drained bag and squeezed it pretty well. I boiled for 60 minutes and strained cooled wort thru a 5G paint strainer bag. Had a total efficiency of over 80%.

I noted when I racked into fermenter I had over 6G of wort. In the end, when I racked into the soda keg leaving .5G of yeast cake in FV, I had over 1/2G of wasted wort. Long story I missed my mark by .5G but not sure why? If I adjust this the right way, I need to put in my corrected grain absorption and or boil off. Just not quite sure how to figure what it off in my numbers.

It is simple to back off one half gallon of strike water, but I'd like to have better numbers to plug into the program. Thanks in advance for any suggestions.

 

[kh54s10]

It sounds like your boil off rate is less than what you have BS set for. I find it varies a little with weather etc. So I would correct in small steps so that you don't end up short.

 

[hellesyeah]

It sounds like your boil off rate is less than what you have BS set for. I find it varies a little with weather etc. So I would correct in small steps so that you don't end up short.

Since I am near sea level close to the coast in SC, and the humidity is already very high, will this be a factor in my boil off rate? In fact, on a GPS program I use for Run Keeper, I am only 77 feet above sea level at my home.

 

[agrazela]

What kind of burner (or electric?) are you using? It does sound like you are overestimating boil-off.

And/or grossly overestimating grain absorption...are you a bag-squeezer?

 

[hellesyeah]

What kind of burner (or electric?) are you using? It does sound like you are overestimating boil-off.

And/or grossly overestimating grain absorption...are you a bag-squeezer?

I use a propane burner which is a turkey fryer burner that the pot fits on precisely to its outer ring. I manage the heat to keep the wort "rolling gently" but not crazy boiling.

Yes, I squeeze the bag but not to the point of busting the seams. A firm but mindful squeeze. Its not dripping when I finish.

 

[Oginme]

Since you are doing a full volume BIAB, the calculations are pretty easy to figure out your actual losses to grain absorption and boil off.

You will need to measure and record as accurately as you can the volume of water in, the volume of wort out and the gravity of the wort before and after mashing. You will need to correct volumes to room temperature and the difference will be the amount of water absorbed by the grain. You can then figure out your grain absorption as qts of water lost / ounces of grain mashed.

This number gets entered in the standard global settings for BeerSmith which you can get to by clicking on 'options' >> 'advanced' > 'BIAB grain absorb' [this is assuming that you are using a biab mash profile]


Next measure the amount of wort left after the boil and the gravity post boil. Correct the volume to room temperature and the difference between the pre-boil volume and post boil volume will be you boil off. Divide this number by the amount of time you boiled and you have your boil off rate.

Your boil off rate you can enter in your equipment profile

 

[hellesyeah]

Since you are doing a full volume BIAB, the calculations are pretty easy to figure out your actual losses to grain absorption and boil off.

You will need to measure and record as accurately as you can the volume of water in, the volume of wort out and the gravity of the wort before and after mashing. You will need to correct volumes to room temperature and the difference will be the amount of water absorbed by the grain. You can then figure out your grain absorption as qts of water lost / ounces of grain mashed.

This number gets entered in the standard global settings for BeerSmith which you can get to by clicking on 'options' >> 'advanced' > 'BIAB grain absorb' [this is assuming that you are using a biab mash profile]


Next measure the amount of wort left after the boil and the gravity post boil. Correct the volume to room temperature and the difference between the pre-boil volume and post boil volume will be you boil off. Divide this number by the amount of time you boiled and you have your boil off rate.

Your boil off rate you can enter in your equipment profile

Thank you for the detailed instructions. I have seen the pre-mash gravity reading asked for before but not sure how to do it? Say my strike water temp is 155F. I ease my bag in and add my crushed grains. Is this when I take a gravity reading of the wort before it has mashed for 60 min? I was not sure when to do that reading. I know I am shifting gears here to an efficiency question.

 

[TexasWine]

and the gravity of the wort before and after mashing.

Did you mean before and after boiling? A gravity reading before the mash isn't going to tell you much

 

[kh54s10]

Thank you for the detailed instructions. I have seen the pre-mash gravity reading asked for before but not sure how to do it? Say my strike water temp is 155F. I ease my bag in and add my crushed grains. Is this when I take a gravity reading of the wort before it has mashed for 60 min? I was not sure when to do that reading. I know I am shifting gears here to an efficiency question.

You need a temperature that is "strike temperature". This is the temperature of the water before you add the grains. This will be different depending on how much grain and what temperature the grain is.

After the mash, usually 60 minutes is when you take a preboil gravity reading. This is to confirm you have the right gravity from the mash. If it is wrong then you can make adjustments. Either mash longer, add a fermentable (usually DME) or dilute it with more water. Or leave it alone.

Your OG (original gravity reading is taken after the boil and it is cooled to the calibration of your hydrometer.

 

[kh54s10]

Since I am near sea level close to the coast in SC, and the humidity is already very high, will this be a factor in my boil off rate? In fact, on a GPS program I use for Run Keeper, I am only 77 feet above sea level at my home.

Altitude has some effect, temperature and humidity will have more.

You just need to make changes in BS over a few brew sessions until you are usually getting the close to the right amount into the fermenter. You will never get it to be exact, since how much you drain out of the grain and how much will boil off will vary a little with each session.

 

[hellesyeah]

You need a temperature that is "strike temperature". This is the temperature of the water before you add the grains. This will be different depending on how much grain and what temperature the grain is.

After the mash, usually 60 minutes is when you take a preboil gravity reading. This is to confirm you have the right gravity from the mash. If it is wrong then you can make adjustments. Either mash longer, add a fermentable (usually DME) or dilute it with more water. Or leave it alone.

Your OG (original gravity reading is taken after the boil and it is cooled to the calibration of your hydrometer.

Great info and from ohginme. I keep reading about how to calculate efficiencies and wondered about the preboil gravity. So I'll take this reading after I drain my grain bag. Then, after the boil, I'll take another reading. Thanks.......makes sense now.

One more rookie question as I am well off track. My preboil gravity should be a small amount lower than my post boil gravity...right? Considering boil off will reduce and concentrate the wort for the post boil reading...or am I confused?

 

[doug293cz]

...

One more rookie question as I am well off track. My preboil gravity should be a small amount lower than my post boil gravity...right? Considering boil off will reduce and concentrate the wort for the post boil reading...or am I confused?

Correct. In fact:

Pre-Boil Volume * (Pre-Boil SG - 1) = Post-Boil Volume * (Post-Boil SG - 1)​

When both volumes are corrected for thermal expansion to the same reference temperature.

You might also want to check out this calculator. I find it much easier to use than BeerSmith for volumes, all the profile information is on one page, and it does some very nice efficiency calculations for you.

Brew on

 

[daveMN]

^^this will get it done for you. I use the Priceless calculator and it has worked well for my water calcs.

 

[Oginme]

Did you mean before and after boiling? A gravity reading before the mash isn't going to tell you much

Yes, you are correct. Thanks for clarifying that for the OP.

 

[Oginme]

Correct. In fact:

Pre-Boil Volume * (Pre-Boil SG - 1) = Post-Boil Volume * (Post-Boil SG - 1)​

When both volumes are corrected for thermal expansion to the same reference temperature.

You might also want to check out this calculator. I find it much easier to use than BeerSmith for volumes, all the profile information is on one page, and it does some very nice efficiency calculations for you.

Brew on

This is a reliability check you should run when using your measurements to 'dial-in' your process. If the equation does not even come close to producing the same number (within the margin of error of your worst accurate measurement), then you should not rely on those numbers too heavily.