Planning first BIAB, some questions...

[jivex5k]

Well I'm going for it....have a quandary though.

My pot is 5 gallons, so I can mash (going to be a light one here) probably 3.5 - 4 gallons comfortably since I'm making a Berliner Weisse.
Originally I intended on going with a 2.5 gallon batch, but this will need to be racked onto fruit in a secondary.
My secondary is 5 gallons, this will leave a crapload of headspace....

So, should I not worry about the headspace, or should I just mash 3.5-4 gallons and top off to 5 after the hop boil?
How could I adjust for this dilution, mash more grain than required? Taste it as it sours and wait til it's a bit more sour than intended?

Thanks in advance!

[bucknut]

I don't believe the extra head space would be an issue, can't think of anything that may cause you an issue but someone else may have another opinion. You could just use an extra pound or two of dme to account for the dilution and do a 5er.

[jivex5k]

Yeah another forum said it shouldn't be an issue as well, mentions the fruit tends to cause c02 production in the secondary.
Gonna start small and go with 2.5 gallons, see how it works out. I've got to figure out my boil off rate now.

[John Sand]

Do what you are comfortable with. I routinely mash and boil 5 gallon batches in a 5 gallon pot. I fit 11lbs of grain in about 3.5-4 gallons BIAB for the mash, then squeeze and dunk sparge the grains to 4 gallons in the pot. Start the boil, after hot break add hops and top off to 4.5. Top again as it boils off, then again in the fermenter. No grain adjustments are necessary, my mash efficiency is consistently 70%.

[myhorselikesbeer]

I do the same as John and get 70-80% eff. I do hope for a 10 gallon pot for my birthday to accomodate full boils and account for break loss.

[John Sand]

I recently bought a 30qt, and tried my first full boil. Still had to adjust water though.

[jivex5k]

Thanks John, I will follow your advice, it's only a 6lb of grain recipe so it should fit fine if you can do 11lbs.

A second question came up though, how much water do I put in for the mash? Am I going to fill it as much as possible, or just enough to cover the grains?

I ask because I won't be sparging until about 4 days after the mash, have to let the lacto innoculate to sour the mash, then I can remove the grains and proceed to boiling the hop schedule. This is where I could top up with a sparge, theoretically eliminating the dilution it would cause if I would top off with just water.

[John Sand]

I would use as much as fits. But I think you are easily safe with 3.5 gallons. If you want a full pot, heat 3.5 in your mash pot, and another gallon in another pot. Then dough in, and top off as necessary. Don't get too crazy about the mash temp, close is good enough. I don't worry if I'm off a couple of degrees.