Hi iijakii & welcome!
I'd recommend doing a standard- sized batch to start with to get familiar with the process, so follow
the Mini BIAB instructions with about 2kg of malt for the first one, maybe do that a few times unless you're cocky and want to start sparging and farting about straight away.
WRT that recipe, I try not to force a brewing application to conform to BIAB, there's no real need, but that one should work all right I think. The main thing is, keep that pot full to the brim at mashing, if you're following the guide it should be a given. Don't sweat the details though, you have to do something majorly bad to not get decent beer out at the other end!
BTW, minifridges are a PITA, go for a bigger one- you can fit more batches in. My big fridge fits four batches at once if things are busy...
Now, if we're all relaxed and ready (deep breath, because I haven't finished my guide for this process, here beginneth RdeV's oft- loathed essay!), we'll look at a full- sized
grain bill, sparging, and over- gravity boils. They're pretty easy to be honest, not overly complex if you've done the straight Mini- BIAB before. It goes like this:
1) Use about 4.5 kg
grain bill in a 19 L stockpot (I do this regularly for 21L to 25L batches of ESB).
2) Fill the pot to the brim at mashing, but always under- fill the initial strike volume, add the
grain and then top up with temperature- adjustment water. So, about 2/3 fill the pot with water, heat it to mash temp + 4 C and add the
grain, then adjust volume and temperature with hot or cool as circumstances dictate. Do not panic if the temperature is not spot on, your beer will still be just fine.
3) Time and temperature stay the same as before- there is no avoiding the basic fundamentals. Start heating your sparge water before the mash is finished though.
4) Lift the bag and drain/ squeeze well, then put the pot on the stove to get it up to boiling (takes a while).
4a) While that's happening, dunk sparge the bag at least once with 1.5 L water/ kg of
grain of near- boiling water, so drop the bag in, open it up, stir and leave for 15 minutes (stir as often as you like), lift the bag, drain and measure the runnings, if >1.030, then do it again, you're losing precious SG points if you don't (may need another bucket).
5) Add the sparge liquor to the pot, again, this is when you want the pot as full as possible. Measure the pre- boil SG after you've added the sparge liquor.
6) With the boil underway, add hops as per the schedule. However, if the boil SG is >1.050 (it should be with that
grain bill) adjust hops additions for utilisation, which means that for every 0.010 over 1.050, increase the hops additions by 10%. (Nb. Don't sweat over this, it really isn't a biggie, more of a technical detail- our senses are probably not so finely tuned as to notice the difference anyway.)
7) Chill in the sink as per the Mini BIAB guide, but just as the boil finishes, get a sample and measure the post- boil SG. (Nb. In the interests of sanitation, sample this from the still- boiling wort!)
8) When it has cooled to pitching temp, work out the post- boil dilution:
Target SG / Actual post- boil SG * Actual Volume = Diluted Volume
SGs such as 1.050 expressed as 50, so with that as the target, 1.075 as the actual and say 16L as the actual volume in the pot, it would be:
75 / 50 * 16 L = 24 L, so the dilution would be with roughly 24 L
less 16 L = 8 L of plain water. Add that to the fermenter, pour in your wort as per the guide, in most cases you'll get the target SG, give or take a few points. Happy days!!!
You'll note that there's a few opportunities to take SG and volume measurements. The important ones are pre- boil SG (to adjust hops additions, which is optional anyway), sparge runnings SG (decide to re- sparge), plus post- boil SG and volume.
Also, if the boil is losing lots of water to evaporation (it should lose 5% or more per hour), top it up with either more sparge liquor from the second sparge or just boiling water. When the boil is finished, the more you have in the kettle the
less you'll lose to trub (through a lower concentration).
It doesn't really matter what the actual post- boil concentration is though as you'll be diluting it later anyway, so there's no need to fuss over 'hitting targets' etc. This diluted or target SG is the most important part, all of the other SGs and volumes are just for 'guidance' whereas the post- boil SG and volume dictate what goes into the fermenter. That's why I don't put much emphasis on getting the software to behave or focus on the actual SG or volume values up until that point, they are not really as important as those values.
Sorry, that was probably a bit too much detail (I really should finish that guide!), but I'm happy to clarify. Feel free to post in the
MiniBIAB forum.
Hope this helps!
RdeV.
Use this thread to convert recipes to suit your equipment...
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