How Much Water Should I Use For BIAB?

[SchweikhardBrewing]

I've been homebrewing for a year now. I've done several extract kits and now I'm getting into BIAB. I did my first BIAB about a month ago and when it came to water volumes I was very confused even after a lot of research.

I want to keep brewing on the stove top so I don't have to buy more equipment. I have a 5 gallon pot so I know if I'm going to do full volume boils, that limits my batch size to about 3 gallons. (I boil off about a gallon of water in a 60 min boil and I'm not comfortable having more that 4 gallons of wort boiling in my gal pot) And I'm fine with this, I actually prefer just 3 gallons at a time instead of 5.

So with all this in mind, for my first BIAB, I basically took a 3 gallon BIAB recipe and guessed on the water amount until I ended up with 4 gallons of pre-boil. I wanted to do a dunk sparge so I mashed in my 7.75 lb of grain in about 2.5 gal of 160 degree water in my pot and let it sit at 152 degrees in a sleeping bag for an hour. Then for the dunk sparge I poured 170 degree water on the grains in a plastic bucket until I had a total of 4 gal of wort between the two vessels and let that sit for 10 min. I think I got lucky and ended up with exactly 4 gallons of pre-boil wort and boiled off exactly 1 gallon to end up with 3. I bottle it today and I seems like it's going to turn out nicely.

I'm working on planning my next BIAB and it's a 3 gallon recipe with a 10.5 lb grain bill. (Imperial Porter) I now have a 60 quart cooler so I can fit all the grain and water I need in one vessel.

What I would like to do instead of a dunk sparge is just dump in more water to the mash tun to bring it to 170 for the last 10 min. The problem is I have no idea how much water to use for the mash and the sparge water. I really would like to be much more precise in this process and use online calculators. I hear for BIAB, a good general rule for amount of water is 1.5 quarts per lb of grain but that's when you do a no sparge, right? What about if I'm doing a sparge? Do I make sure the total water after the sparge is 1.5 quarts per lb of grain? Will that leave me at 4 gallons of pre-boil wort?

Please help me understand the best way to go about being more precise in calculating my brew day. Cheers!

 

[Jeff_T]

I've been using this site for my water volumes for the last few batches and it's worked out pretty well. http://simplebiabcalculator.com/

 

[Biscuits]

https://pricelessbrewing.github.io/BiabCalc/#Advanced

 

[nobadays]

+1 on Priceless calculator. Simple to use and highly accurate!

Want to add... many if not most biab brewers skip the mash out/sparge step completely if they can do full volume and it sounds like you can now. Brulosophy did an exbeerment side by side to standard and cold water sparge and found no difference. See: http://brulosophy.com/2016/04/11/sparge-temperature-pt-1-standard-vs-cool-exbeeriment-results/

I just lift my bag and squeeze the bejezus out of it and always get 85-90% efficiency.

Cheers!

 

[pricelessbrewing]

I've been using this site for my water volumes for the last few batches and it's worked out pretty well. http://simplebiabcalculator.com/

Now I'm obviously biased towards my own software, but...

I cannot recommend this one, as it has multiple issues. The largest of which is that it uses 0.125 gal/lb as the grain absorption rate which is typical for a mashtun setup and is not true if you're lifting the grain bag out of the mash, or squeezing. Which most biabers do.

Thanks for the plug guys!

 

[Jeff_T]

Now I'm obviously biased towards my own software, but...

I cannot recommend this one, as it has multiple issues. The largest of which is that it uses 0.125 gal/lb as the grain absorption rate which is typical for a mashtun setup and is not true if you're lifting the grain bag out of the mash, or squeezing. Which most biabers do.

Thanks for the plug guys!

Thanks for the heads up and thanks for the work you put in creating yours. I'll def be using it from now on.

 

[SchweikhardBrewing]

many if not most biab brewers skip the mash out/sparge step completely if they can do full volume and it sounds like you can now.

Interesting. So if I decided to go this route (no mash out/sparge), I would just add water of the amount of wort I want to end up with plus the calculated grain absorbtion amount (I've read about half a quart per lb of grain?) all at mash in still doing 150-158 degrees for an hour? And I can basically forget about the additional 10 minutes I mentioned? Sounds a lot easier!

Also, what kind of efficiency do you think I would get if I didn't squeeze the bag?

Thanks

 

[pricelessbrewing]

Interesting. So if I decided to go this route (no mash out/sparge), I would just add water of the amount of wort I want to end up with plus the calculated grain absorbtion amount (I've read about half a quart per lb of grain?) all at mash in still doing 150-158 degrees for an hour? And I can basically forget about the additional 10 minutes I mentioned? Sounds a lot easier!

Also, what kind of efficiency do you think I would get if I didn't squeeze the bag?
Thanks

If you're neither lifting nor squeezing, then you can expect ~0.125 gal/lb absorption rate, and if you squeeze and allow to drip dry fully, or squeeze you should expect ~0.08 gal/lb.

As far as efficiency, it is a complicated question that will vary depending on your boil off rate, how you sparge (if you do at all), what your absorption rate is, what your boil off rate is, and what the recipe is. You can get a good estimate using my software, but other than that you're unlikely to get a trustworthy guess without answering all of the above variables.

 

[nobadays]

+1 Priceless... The only thing I would add is that there is no reason not to squeeze the bag, or in some way try to get as much wort out of the grain as you can...I only have one arm so I twirl it around and around twisting it tight then squeeze as much as I can to get all the wort out as possible. The old myth about releasing tannins by squeezing the grain bag - usually referring to steeped grains - has been debunked long ago.

Somewhere in the BIAB thread I remember reading that someone took an S.G. reading before squeezing the bag then another after and the difference was quite a rise in S.G. Some do not squeeze the bag but place it on a rack over the kettle to drain, others - like myself with a way to winch the bag out of the kettle - just let it hang and drain while the wort is coming to boil.

The point is, get all those good sugars you can out of that grain! Squeeze the bag already:rockin:

edit... Priceless's calculator seems to be almost dead on for O.G in my experience!

Cheers! Don

 

[doug293cz]

...

Somewhere in the BIAB thread I remember reading that someone took an S.G. reading before squeezing the bag then another after and the difference was quite a rise in S.G. ...

This can happen, and maybe even does frequently. But, if it does, it means that your process is less than optimal. Two things can cause this to happen, either alone or in combination:

1. If your starch to sugar conversion is not complete when you start draining your bag, then conversion can continue in the grain mass during the draining. Then when you squeeze, you get higher SG wort then on the initial draining. You want conversion to be complete at the end of your mash, otherwise your conversion efficiency will be less than 100% and your mash efficiency will also be lower than it should be. This also means that the wort absorbed by the grain is the highest SG wort which reduces your lauter efficiency, which also reduces your mash efficiency. A double whammy.
2. If you don't stir the mash well enough prior to draining. The converted sugar is going to be preferentially absorbed in, or clinging to, the grain particles (grits.) This will cause your wort absorbed by the grain to be higher SG than the drained wort, meaning you are leaving more sugar behind than you should be. Again lowering lauter efficiency and mash efficiency. You want to stir your mash vigorously prior to draining so that the initially higher SG wort in and on the grits is equalized with the bulk wort. This will minimize the amount of sugar in the wort absorbed by the grain, thus improving your lauter efficiency. Unfortunately there is no way to get the bulk wort to be higher in SG than the absorbed wort.

If your conversion is complete and your wort well mixed, then the first runnings and the squeezed runnings will have the same SG, and you will have optimized your mash efficiency.

To insure that your conversion is complete, compare the SG of the wort in the mash (after stirring) with the value that corresponds to your mash thickness (qt/lb) in the table here. If your SG is significantly less than the table value, you are not close to 100% conversion, and you should mash longer. You can speed up your conversion by crushing your grain finer (biggest effect), mashing thinner, and insuring your mash pH is in the range 5.3 to 5.6.

Brew on

 

[doug293cz]

I think it's helpful for brewers to have a basic understanding of their brewing water volume requirements. It's not particularly difficult, and the math required is really simple. It's easiest if you work backwards from your desired fermenter volume, and then add in the volume losses at each step, starting with racking to the fermenter back to the mash.

First, calculate your target post-boil volume. This is just equal to your target fermenter volume plus the volume you leave in your kettle (trub allowance) plus the volume retained in any plumbing. If you are brewing a highly hopped beer you might want to include extra trub loss for hop absorption. If, like many BIAB'ers, you just dump everything from the BK into the fermenter, then target post-boil volume is equal to target fermenter volume.

Second, calculate your target pre-boil volume. This is just equal to your target post-boil volume plus your total expected boil-off volume. Total expected boil-off volume is equal to boil-off rate (in gal/hr) times boil time (in hrs.)

Third, calculate your total brewing water volume. This is equal to your target pre-boil volume plus your expected grain absorption. Expected grain absorption is equal to the grain absorption rate (in gal/lb) times the grain bill weight (in lbs.) Also, if you are using an MLT that has some undrainable volume, you need to add that as well.

If you are doing a full volume mash with no sparge, then your strike water volume is equal to your total brewing water volume

If you are going to batch sparge, then use 60% of your total brewing water for strike, and 40% for sparge. This will insure that you are close enough to equal run-off volumes for first runnings and sparge runnings, and will maximize your lauter efficiency.

You'll notice that nowhere above was anything said about mash thickness. That's because you really only need to worry about that if you are going to fly sparge, or if you are brewing with a very large grain bill, where if you only used 60% of your total brewing water for strike, you would end up with a very thick mash. So if you are brewing a big beer, you should also calculate the volume of water that would give you a 1.25 qt/lb mash thickness. If this volume is more than 60% of your total brewing water, then you should use the larger volume for your strike volume. And then the remainder of your total brewing water for sparge.

Of course the Priceless calculator (and others) will do all the math for you if you input your grain bill, grain absorption rate, undrainable MLT volume, boil-off rate, boil time, batch size target (fermenter volume), kettle losses, etc.

Edit: For OP's case of a 10.5 lb grain bill for a 3 gal batch, with sparge, the 60:40 rule of thumb would result in mash thickness of about 1.1 qt/lb, so the thick mash exception should be used to calculate strike and sparge water.

Brew on

 

[Horseflesh]

You want to stir your mash vigorously prior to draining so that the initially higher SG wort in and on the grits is equalized with the bulk wort.

Never read this before but it makes a lot of sense!

 

[nobadays]

Thanks Doug! Very simple explanation of brewing water volumes calculations, a local brewmaster taught me this method as well. However I do like using Priceless's calculator though, more information in short order! In my experience it is also very accurate.

Stirring makes sense, based on your explanation of what is happening with the sugars and grain... but like Horseflesh I had never read this before. I have never stirred before lifting the bag, but I also do a 90 minute mash - every mash - and recirculate the wort for that entire 90 minutes, so basically stirring the wort.

Still gotta say...squeeze/drain that bag and get all the wort you can out of it!

Cheers! Don

 

[SchweikhardBrewing]

If you are doing a full volume mash with no sparge, then your strike water volume is equal to your total brewing water volume

If you are going to batch sparge, then use 60% of your total brewing water for strike, and 40% for sparge. This will insure that you are close enough to equal run-off volumes for first runnings and sparge runnings, and will maximize your lauter efficiency.

You'll notice that nowhere above was anything said about mash thickness. That's because you really only need to worry about that if you are going to fly sparge, or if you are brewing with a very large grain bill, where if you only used 60% of your total brewing water for strike, you would end up with a very thick mash. So if you are brewing a big beer, you should also calculate the volume of water that would give you a 1.25 qt/lb mash thickness. If this volume is more than 60% of your total brewing water, then you should use the larger volume for your strike volume. And then the remainder of your total brewing water for sparge.

Thank You!

This is what I was looking for. Now this makes sense to me. I think I will try the full volume mash with no sparge to make things simple. Here's my calculations:

3 gal post boil
1 gal boil off
.84 gal grain absorption

Total volume: 4.84 gal

This gives me a 1.84 q/lb mash water to grain ratio (yes this is a big beer, I know it would normally be over 2 for a full volume mash)
Strike water temp: 164.2 F
First Rest temp: 155 F

Let it sit for 60 min then let the bag fully drain over the MT sitting on a cooling rack. Drain into my BK and boil.

Let me know what you guys think!

 

[doug293cz]

Thank You!

This is what I was looking for. Now this makes sense to me. I think I will try the full volume mash with no sparge to make things simple. Here's my calculations:

3 gal post boil
1 gal boil off
.84 gal grain absorption

Total volume: 4.84 gal

This gives me a 1.84 q/lb mash water to grain ratio (yes this is a big beer, I know it would normally be over 2 for a full volume mash)
Strike water temp: 164.2 F
First Rest temp: 155 F

Let it sit for 60 min then let the bag fully drain over the MT sitting on a cooling rack. Drain into my BK and boil.

Let me know what you guys think!

Sounds like a plan. Don't forget to stir well at the end of the mash. If you hit your volume numbers, and get 100% conversion in your mash, your pre-boil SG should be about 1.067 - 1.068, your post-boil SG (OG) about 1.090, and you mash efficiency about 73%.

If you did do a sparge, strike water volume should be 3.28 gal, sparge 1.56 gal, pre-boil SG would be about 1.075 - 1.076, OG about 1.101, and mash efficiency about 81 - 82%.

Brew on

 

[doug293cz]

Thanks Doug! Very simple explanation of brewing water volumes calculations, a local brewmaster taught me this method as well. However I do like using Priceless's calculator though, more information in short order! In my experience it is also very accurate.

Stirring makes sense, based on your explanation of what is happening with the sugars and grain... but like Horseflesh I had never read this before. I have never stirred before lifting the bag, but I also do a 90 minute mash - every mash - and recirculate the wort for that entire 90 minutes, so basically stirring the wort.

Still gotta say...squeeze/drain that bag and get all the wort you can out of it!

Cheers! Don

I'm not advocating doing calculations by hand, just advocating understanding what the calculations are all about. Then the inputs that the calculator is asking for make more sense, and the user has a better chance of providing good input. I also use and recommend Priceless's calculator (after all, I did help get it to where it is today.)

Yes recirculating does help to equalize the wort concentration, but stirring provides much more shear, so acts faster. If you figure out the flow velocity for recirc, it's a lot lower than what you get with stirring. Time can also help equalize wort concentration, by allowing diffusion to run its course. But again, stirring is much faster.

Yep, squeeze, squeeze, squeeze. The less wort you leave in the grain, the higher your lauter (and mash) efficiency. Unless of course, getting high efficiencies isn't one your priorities (which is a valid choice.)

Brew on