# Maxi Biab And Post Boil Dilution



## Truman42 (11/11/11)

Im using the maxi BIAB technique to do a 17 litre batch in my 18 litre pot. I've used the MAXI BIAB calculator which tells me I need 4.84 kgs of grain from my recipe to get SG 1.060.

In the MAXI BIAB tab it has this

Pre-Boil Addition	5.27	L	if you are not able to perform a full volume mash, then you may need to top up your kettle to Start of Boil Volume	

Boil Additions	4.54	L	if you are not able to perform a full volume boil, then you may need to top up your kettle during the boil 

Fermenter Dilution Required	4.48	L	if you are not able to perform a full volume boil, you may need to use Post-Boil dilution, which is best done in the fermenter	

So does this mean I should sparge and add the sparge to pre-boil and during boil additions? Or does it mean to add fresh water?

The calculator says my start of boil SG will be 1080. And I want an end of boil SG of 1060. If I just kept adding sparge water wouldn't that mean my SG would remain high to the point that I couldn't add a fermenter dilution of water required to bring it back to 1060, without going over my cube volume of 20 litres?	

Where as if I add water during the boil it will reduce my SG to say 1070 then I could add more water in my fermenter to bring it down to 1060?

Not sure which way to go here and would appreciate some advice from other Maxi BIABers.


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## Nick JD (11/11/11)

Geez, you really love to make this complicated, don't ya! 

My first advice would be to stop firing off numbers in long winded posts asking for help. They make it impossible to understand what you are actually asking. 

Just mash, sparge and then top up with whatever amount you need to get to your maximum safe boiling level. 

Measure the SG and the volume and this will tell you _how much you can dilute._ You cannot boil 17L in an 18L urn. So just boil whatever you get and then dilute with boiling water into your nochill cube.

And again - for the third time now - UNLESS YOU KNOW YOUR EFFICIENCY YOU CAN'T CALCULATE ANYTHING! You are assuming that you'll hit all these targets. 

Sorry for the yelling but I'm running out of help juice. After all thos PMs about this very same subject and you're asking again? Didn't we already work this out? :huh: 

So now I have to say: do you realise that everybody doesn't get the same amount of stuff from the same amount of grain? If you get 60% efficiency you'll be nowhere near what someone who gets 85% would get - and since you don't know this it's almost useless trying to ask for these steps when you don't know the important numbers.

Again - just make it. This will all become clear. Write it all down and then .... you'll know next time!


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## [email protected] (11/11/11)

ey champ

I dont use the calculator, i use BS1 i find it easier and more accurate.

One of the founders of MAxiBIAB might come along and answer your questions 
more directly,but il give you a run down on what i would do and you take on board anything
you find useful. 

Based on 75% efficiency
OG estimate 1063 
Pre boil gravity 1072

4.8kg of grain, mashed at 3L/ kilo will take up about 17.5L of space.
So right at the top for your pot.

So thats 14.4L of water, say you loose 0.5L of water/kilo to grain absorption
this will leave you with about 12L after mash.

You could then rinse the grains with 3L of water, giving you preboil 
of 15L, which for me would be the highest i would want to go in 18L
pot - depending on how violent your boil is.

When doing high gravity boils, i usually just boil to my full capacity
and at the end top up with boiling water, so when it comes to racking
into cube or fermenter, any losses will not be so concentrated in regards
to high specific gravity. 

A brewing program will help you work out and keep track of what % you will
loose to evaporation during the boil and how much you will need to dilute into the fermenter.
Is also great for working out how much hops to use and when.
Depending on your mash efficiency you may need to recalculate your additions
to suit the pre boil gravity. Higher gravity means more hops

Just my 2 cents mate, get to know a brewing program and it makes things heaps 
easier.

cheers


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## Truman42 (11/11/11)

@NickJD...Mate..Mate...All I was asking..In a long winded round about sort of way is should I top my boil up with sparge water even though my SG will be quite higher than what I require, and try to dilute this down with water in the fermenter.

Or should I top up during the boil with fresh water to help reduce the SG as I go and therefore not requiring so much water in the fermenter.

As far as efficiency goes and working it out roughly from my last brew and the figures I recorded Im getting higher than 80% efficiency.

But thanks once again for the advice.

@Beer4U...I use brewmate but it doesnt really calculate for MaxiBIAB and sparging etc. The MAXIBIAB calculator tells you how much water to use etc and then what to top up with in the ferm. Just was unclear about the boil additions.
I will top up with boiling water during the boil and keep taking SG readings and see how close I get to my SG when I rack. Thanks again for the advice.


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## stux (11/11/11)

Truman said:


> Im using the maxi BIAB technique to do a 17 litre batch in my 18 litre pot. I've used the MAXI BIAB calculator which tells me I need 4.84 kgs of grain from my recipe to get SG 1.060.
> 
> In the MAXI BIAB tab it has this
> 
> ...



For the maxi-biab calculator to work accurately, you need to know your boil-off rate. If you do, then its numbers should be pretty accurate. If you're not sure about your efficiency, then use 75% or so and if you go over, you'll just end up with more beer.

If you have sparge water you can use that instead of fresh water for your topups, as long as you don't add the sparge water after about 10-15 minutes left to go in the boil

BUT it shows you two sets of numbers... the estimates, and the actuals.

If you've entered your limits, and evaporation, etc, then do you mash according to the recommendations... pull your bag, sparge etc...

and then take your Start of Boil / Gravity readings and enter those into the calculator. It'll up date the end of boil target for you, based on your actual gravity and volume.

(and your hop additions too)

Just add water or sparge water during the boil so you end up at the updated end of boil volume by the end, then you can cube what you have.

or just let it boil down and cube what's left.

when you dump your cube into your fermenter, enter the volume and gravity and the calculator will tell you how much topup water to use

The reason you add water during the boil is to minimize losses to the trub. The higher the gravity at the end-of-boil, the more loss you will make from the kettle trub. So the ideal situation is to have cube volume + kettle loss left at the end of boil.


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## stux (11/11/11)

"Post-boil dilution" aka Fermenter dilution is done in the fermenter, not in the cube.

You have an 18L pot. There is no way you're going to overfill your 20L cube 

just top up your boil during the boil so that you leave enough headspace to allow you to safely do a whirlpool at the end


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## stux (11/11/11)

Truman said:


> @Beer4U...I use brewmate but it doesnt really calculate for MaxiBIAB and sparging etc. The MAXIBIAB calculator tells you how much water to use etc and then what to top up with in the ferm. Just was unclear about the boil additions.
> I will top up with boiling water during the boil and keep taking SG readings and see how close I get to my SG when I rack. Thanks again for the advice.



The primary reason for the boiling water topups is to counter-act evaporation. If you have sparge water you will be able to increase your efficiency by using it instead of fresh water.

No reason not to 

...

I think after reading a bit more you might be fermenting in the cube? If that's the case, you should probably tell the maxi-biab calculator that your not using a cube (0 for max-cubed volume)

And then you can just target your final fermenter volume (20L?). The limit will probably be your end-of-boil limit, which I imagine is 16 or so L, rather than your cube size anyway


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## Truman42 (11/11/11)

Stux said:


> The primary reason for the boiling water topups is to counter-act evaporation. If you have sparge water you will be able to increase your efficiency by using it instead of fresh water.
> 
> No reason not to
> 
> ...



Yes I am fermenting in the cube.

Here is my recipe summary from the MAXIBIAB tab. But as stated I suppose all I really have to worry about is my EOB SG then work out dilution required with what I get into my 20 litre cube.

Recipe Summary 
All from the Volumes Etc tab 

Brewlength	17.00	L
Grain Bill 4.804	KG
Original Gravity	1.060	SG


BIAB Summary 
Standard BIAB is a Full Volume Mash, all water is added initially 
Standard BIAB	No	

Liquor to Grain Ratio 2.61	L/KG

Estimated Transferred Volume	13.16	L
Estimated Fermenter Volume	17.54	L
Estimated Packaged Volume	16.18	L



Standard BIAB Volumes 
Estimated Cool Water Required 27.76	L
Estimated Warm Water Required 28.27	L
Estimated Standard Mash Volume	31.63	L
Estimated Total Wort 20.40	L


Maxi-BIAB Techniques Utilized 
Maxi-BIAB is a collection of techniques used to increase brewlength, including separate sparging, over-gravity boils, water additions and post-boil dillution 

Pre-Boil Water Addition	Yes	
Boil Additions	Yes	
Post-Boil Dilution	Yes	


This section provides estimates of all volumes and readings so that you can plan your brew day 

Volumes and Estimates 

Dough-in Volume	12.54	L
Mash Volume 15.90	L
Mashout Volume 9.53 L
Start of Boil Volume	15.20	L
End of Boil Volume	15.20	L
Hot Transfer Volume	13.16	L
Cooled Kettle Volume	14.55	L
Cool Transfer Volume	12.51	L
Fermenter Volume	17.54	L
Packaged Volume	16.18	L

Additions 
Additions may be required if you pot is not large enough for a Standard BIAB 
Pre-Boil Addition 5.29	L
Boil Additions 4.54	L
Fermenter Dilution Required	5.03	L


Gravities 
Start of Boil Gravity	1.084	SG
Average Boil Gravity	1.084	SG
End of Boil Gravity	1.084	SG
Into Fermenter Efficiency	71.4%	
Into Packaging Efficiency	65.8%	



> You have an 18L pot. There is no way you're going to overfill your 20L cube



That's what I was looking for. I thought with an SG so high 1080 and with top ups of sparge water I may run out of room to dilute back to 1060.

Last brew I stuffed up on the levels because I don't think my wife wrote down the measurements I gave her properly, so wasn't 100% sure on the litres I had at EOB.  
Also I had to cube into 2 x 10 litre cubes then rack to my 17 litre cube so I lost trub in both of them. This time around I will mark litres on my 20 litre cube and check and double check the EOB litres and kettle trub to get some more accurate figures.

Thanks again fro your advice.


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## stux (11/11/11)

View attachment Dilution_Scaler.xls


Little dilution scaler excel, you might find it handy


If you have 14L at 1.080, that's 18.66L at 1.060

15L would be 20L at 1.060


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## stux (11/11/11)

I would be concerned about your mash thickness. 2.61 is very thick for a BIAB. 

You really will *need* to use a sparge step

You need 5.5L of pre-boil topup, and 4.5L during the boil, so pretty much sparge your bag twice with 5L each time

If you do that, you should end up with about your efficiency figures.

then add as much of your sparge water as you can before the boil, and the rest during the boil. If you pour it in slowly as its vigorously boiling it won't stall.

...

I'm working on a different calculator, which I've just used to confirm those numbers... BUT you're looking at about 1.097 for the first runnings, which is very high. 

There will be so much sugars lost to grain absorption, that if you don't sparge it just won't work


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## Truman42 (11/11/11)

Stux said:


> View attachment 49988
> 
> 
> Little dilution scaler excel, you might find it handy
> ...




Cheers for that Stux. Will come in handy.


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## Nick JD (11/11/11)

Truman said:


> ...should I top my boil up with sparge water even though my SG will be quite higher than what I require, and try to dilute this down with water in the fermenter.



"Sparge water" will have mash sugars in it - so yes, very much so. 

If you mean "plain boiling water" then yes, add it in until you are at your safe boiling level. If you are already there with returning your sparge runoff, then no.

With high grav brewing (MaxiBIAB ... sounds like a womens' sanitary product for high-flow days) just pretend you're making a watery version of kit goo.


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## Truman42 (14/11/11)

Thanks for the advice, I will sparge twice and see what my SG ends up being at EOB. 

Maybe I should have stuck with minibiab for my third BIAB and mastered that before giving Maxibiab a go. 

But I wanted as much as possible ready for xmas...


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## esssee (14/11/11)

Just my 2c worth.

I BIAB in a 19 litre pot.

13 litres to 4kg of grain for the mash. Any more water, and it's too close to the top of the pot. Any more grain, and you get bugger all extra efficiency.

About 10 - 11 litres after the mash.

"Mash Out" with about 4 litres of water.

Gets about 15 litres Pre Boil.

Which is about 12 litres Post Boil.

About 11 litres into the fermenter, and top up to whatever OG you want.

Hope this helps.


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## Nick JD (14/11/11)

esssee said:


> Just my 2c worth.
> 
> I BIAB in a 19 litre pot.
> 
> ...



That's how I do it too. It really, really doesn't need to be complicated.


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## chunckious (14/11/11)

So Stux, there wont be a problem with adding sparged water "during" the boil. Meaning some of the wort wont get a full 60min boil time.


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## Lord Raja Goomba I (14/11/11)

Not wanting to bag anyone out (because I respect BIAB, after my brew effort last night without it), but....

Have you thought about obtaining an extra pot from Big W (especially on special - my 2nd was $12) and doing a double stovetop? It's my "standard" method.

It means that the strike water heats quicker (heating 2 x 8.5L, is quicker than heating 14 or 17 L, nor do you need to "top up"), and you've got the head room to really give it a good sparge.

Obtaining boil is easy as well.

The only downside is a higher loss to trub (by virtue of 2 pots with an inch in each), but in terms of chasing extra efficiency, it's somewhat offset by the extra ability to sparge.

Goomba


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## stux (14/11/11)

Chunkious said:


> So Stux, there wont be a problem with adding sparged water "during" the boil. Meaning some of the wort wont get a full 60min boil time.



Right. Best to ensure your sparged wort gets at least 15 mins boil time. But other than that, no, no one has ever reported a problem


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## Robbo2234 (14/11/11)

where can I find the MAXIBIAB calculator you speak of?


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## Truman42 (14/11/11)

esssee said:


> Just my 2c worth.
> 
> I BIAB in a 19 litre pot.
> 
> ...



I scaled my recipe using brewmate and the MAXIBiab calculator and it told me to get an EOBG of 1060 with a 17 litre brew length that I needed 4.8 kgs of grain. I thought it was a bit much but I double checked everything I did and thats what they both came back with. I now realise it is too much so will just have to see how I go.

*Original Recipe* 
Grain Name Percent 
Grain Bill Required 100 
Pilsener 78 
Biscuit 6 
Wheat 6 
Crystal medium 4 
Carafa II 3 
Chocolate 3 


Scaled Recipe	
Percent	Weight (KG)
100 4.804
78.0 3.747
6.0 0.288
6.0 0.288
4.0 0.192
3.0 0.144
3.0 0.144


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## Truman42 (14/11/11)

Lord Raja Goomba I said:


> Not wanting to bag anyone out (because I respect BIAB, after my brew effort last night without it), but....
> 
> Have you thought about obtaining an extra pot from Big W (especially on special - my 2nd was $12) and doing a double stovetop? It's my "standard" method.
> 
> ...



Mate I have an 18 litre urn and a 20 litre BigW pot...But Ive just moved house and we have an induction cooker and the pot doesn't work because its aliminium. That and the missus wont let me brew inside anyway. So until I get a burner Im stuck with just the urn.


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## Lord Raja Goomba I (14/11/11)

Truman said:


> Mate I have an 18 litre urn and a 20 litre BigW pot...But Ive just moved house and we have an induction cooker and the pot doesn't work because its aliminium. That and the missus wont let me brew inside anyway. So until I get a burner Im stuck with just the urn.



Ban her from beer until she lets you. Mine started up and I told her that if she kicks me out, she gets no beer.

Works too! :lol: 

Goomba


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## Truman42 (14/11/11)

Lord Raja Goomba I said:


> Ban her from beer until she lets you. Mine started up and I told her that if she kicks me out, she gets no beer.
> 
> Works too! :lol:
> 
> Goomba



Ha ha Yeh good idea I might try it. Dont think it will work though..LOL


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## craigo (14/11/11)

i put my recipe into brewmate and it says to use 2.6kgs to 12L of water for an abv of 4.5% is this correct from what ive read it should be 4kgs of grain to 13L of water.


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## esssee (14/11/11)

Craigo,

The 4kg of grain is for between 19 and 23 litres.

Basically you make a higher concentrated Wort (1.060 to 1.070), and then dilute it to your required OG.

I do my calculation in BrewMate using 21 litres, then use that OG as my target when diluting. If my efficiency was down, I dilute less, and end up with less into the fermenter. If the efficiency is up, I can chose between more into the fermenter at THAT OG, or 21 litres of a higher OG.

EDIT: Just checked my notes, and I was slightly wrong in my earlier post. I have successfully used 5kg of grain in my 13 litres, and only dropped a few points in efficiency.


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## craigo (14/11/11)

oh ok thanks that makes sense


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