I've decided to do a Munich Dunkel (to complement the Helles).

I just bought 25KG each of Weyermann Pilsner and Weyermann Munich I

( I like germans... I married one )

So the recipe will be

8KG of Munich I
2KG of Pilsner
and 200g of Carafa Special III for Colour


All Weyermann

OG will be about 1.052

Hops, I'm still working on, but thinking

Hallertauer 30g 45min
Northern Brewer 30g 45min
Hallertauer 15g 5min

Hoping for 22 IBUs or so

My basic plan is to do a Hochkurz Mash schedule with 49L of mash volume (50L pot)

Top up to 45L for the boil

Top up to 45L during the boil

Top up to 45L towards the end of the boil

And end up with 45L at the end of the boil, and get a nice 40+L of wort out of that.

I figure I should end up with about 45L of 1.055, but I will then just dilute into the fermenter back to 1.052

This is my basic idea of a simplified maxi-biab at double batch scale

So,

I see The Calculator uses grain-weight x 66% to work out grain displacement

So, my grain should displace 7L, so in a 50L pot, starting with 40L and then adding back to 49L after doughin, should be good?

Looks good, just be careful of overflows when you pull the bag.
I'm interested to hear how the hochkurz mash goes.

Immediate Debriefing...

I was pushing my boundaries and had lots of fun

Few notes,

10KG of grain fills a 20L handypail to the brim
10KG of grain displaces 10L of water when dry... which settles down to 7L once the grain is wet, but you do need 10L of space to pour the grain in! (i had left 10L so was just in luck)

Don't forget to allow for the depth of the lid when filling to the brim! My lid uses about 15mm of headspace... so I need 2cm of headspace... which I did not have... putting the lid on is a bad idea like that... luckily after losing a bit of wort, it all settled down, so I now know that I need to allow a couple of cm head, and at least 1L per KG of grain in the mash water... then top up to the head space. Once your bag is wet like that, the capiliary action pulls more liquid out! don't get your bag wet past the rim.

Pulling the bag then left me with 30L...

I estimate I got another 5L or so out of the bag... hard to tell... I topped up to 40L as I boiled.

at boil (ie 100C) I had 40L of liquid at 1.065. Which gives me a pretty damn good efficiency form 10KG

8cm of head space during the beginning of a boil is a bit chancy with boil overs... few tricky moments... when the tides were surging from side to side but after it settled down, I could probably push it

A two ring burner will give you a violent boil with 50L of wort if you crank the gas right up

i was topping up during the boil with boiling water... I didnt have second burner going so, only ended up with 41L of hot liquid (70mm from top of 40x40 kettle) at end of boil

I whirlpooled. Using half a whirlfloc for 40L seems like a good... whirlpool worked excellently!

Managed to syphon so much wort into the cubes... that I only had 600ml of slop left behind!!!

That slop I filtered, and then left to sit... and I could only get half a shotglass of clear liquid out of it! enough to compare the difference pre and post boil, but not enough for a reading! I will have to wait till I ferment these babies to do a post boil grav reading! I estimate the 40L (39L estimated cooled by The Calculator) at 1.065 will be 1.063 with the extra litre (41L measured, 40L by The Calculator (cooled)

I believe I've collected 40L of wort in the cubes at 1.063, diluting to 1.052, that should give me 48.5L

calculator says my Mash efficiency was 82%, and my boil was 80%... not sure about those numbers... the 600ml I left behind was pure trub, after 2 hrs, I still only had 15ml of clear liquid floating on top of the detritus, and that's after sieving.

Beer Alchemy, the iphone beer app I'm using, says I got 81.6% mash efficiency, which concurs with the calculator

80% is what I had estimated...

I should get 80% into the fermenter more or less.


Very impressed with the 1/2 tablet for 40L of wort... seems to have resulted in a denser detritus. I'm estimating i should get enough out of my fermenters to fill more than 2 kegs... so will be happy with that.

Oh, and the beer smells and tastes fantastic... but more when I ferment it!

I would've liked to have ended the boil with hot dilutions to about 45-48L which would've given me a end of boil gravity of about 1.054, whihc is what I wanted, but I didn't have enough boiled water before flamout, and didn't want to disturb the whirlpool. If I could've diluted before cubing, i would've been able to leave 5L behind... which would mean less carry over of the detritus, and I would've had enough left overs for readings and making yeast starters.

After all was said and done, I had an extra 600ml of dark dark slightly tannic runnings from the grain at 1.075. Wondering if I should use that for a starter... it did taste good

I wonder what would've happened to my efficiency if I added the 600ml of 1.075, and if I had bothered to sparge

With the handy pail, it should be quite easy, might try a sparge next time.

After all was said and done, grain weighed 12KG up from original 10KG... does that mean 2L of water in 10KG of grain (not really because all that sugar is gone)

And the grain had very little sweetness.

Hochkurz was great, and lots of fun... I learnt how NOT to do the first step, which is get the wrong temperature, then overshoot, then cool... and how not to raise the temperature... lots of lessons learned... next time will be smooth tho the nice thing is, 3 steps is like 3 attempts to get it right, so very good practise.

The idea behind the hochkurz was to get the beer thick, dark and malty, seemed to have worked

For the 70C rest grain/liquid was very fluid, and darkened fast... gorgeous.

75c mashout, I think I messed up, the liquor went to 74C, then shot to 78C virtually instantly, i think the pot was absorbing heat, and then released it all... so I yanked the bag out asap... which was interesting. Might make for a dark beer, but it seems to taste good... teh recipe was looking on the light side anyway...

boil went perfectly, except, next time I need my second burner with 10L at boiling for my boil time water additions.

I'm definatley pushing the limits of 50L pot brewing I think, but I'm happy, I should be able to get 3 15L cubes out of this pot at a pretty good gravity and pull off a triple batch ferment.

So, maximum mash would be about 45L, and maximum start of boil about 40L, max end of boil, could be all the way up to 47L

20L of grain is a good amount to handle, anymore, would start to get hard... but perhaps 30L could be done.

I was trying to push my equipments limits, and I think I succeeded

My brew partner enjoyed it immensely too.

I will definately hochkurz my next dunkel... after all I still have 17KG of Munich malt left

This was the first recipe I constructed, and so far, it seems good from what I can tell... perhaps the hops need more tuning, hard to tell with all the messed up volumes

Is this Mega-Maxi-BIAB yet?

I would like a 100L pot I suspect I might get one for Christmas

Might be novel to do big triple batches with a single water addition

All water started as 55C Solar Heated water... which is nice.

That's a truly great post stux and worth several reads.

More later but if one of my long posts follows yours above, everyone will stop reading this thread

For now, I'm very glad I stopped and read your post a few times. Top job .

I was thinking about it,

Sparging, in essence, is rinsing the grains to gain any extract which is still attached to the grain. The thicker your mash gravity, the harder it is to extract this "coating", and the better a sparge will work.

This is also the reason we raise the mash to 75C at mashout, to help the sugary residue run-off.

One of the reasons I haven't been sparging my 10KG grain back is my 25L bucket fermenter is in use... and its the perfect size to sparge this quantity.

The 20L handy pail was a good size to hold the full grainbag. But I'm not sure if it would work well for the sparge with a collander in teh bottom...

Maybe I should just get another 25L bucket, but I know, I'd just end up using at as a fermenter again!

I would like to sparge the grains in future, I think my process will be

Mashout and raise bag... let it flow for a while until it cools off... then squeeze it... then dump it into a sparging bucket and hit it with a few litres of near boiling water...

perhaps raise and squeeze again...

and then dump the runnings.

I read on another forum someone tests his sparge water to see what gravity he's getting... giving up at 1.030, or something like... seems like a sensible idea.