Some queries re BIAB from a newbie

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Andrew Jefferies

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Hi All,

I am new to all grain brewing, having tried extract previously. I am dipping my toe into BIAB while I get my bearings. Just a couple of questions from my first brew:

The recipe I used from Grain and Grape, is for a 20 litre brew, with a start volume of 27 litres. My fermenter volume was a paltry 15 litres. Should I top up to 20 litres in the fermenter, or ferment at the volume obtain from my boil.

Also, I used the no chill method to cool the wort. Is it ok to tip the entire contents into the cube, and filter into the fermenter once the wort has cooled to remove residue from the kettle? I can probably get a bit of extra volume, but I am unsure if I would be adding anything nasty too the wort.

Cheers,

Andrew
 
Andrew, the volume on its own is pretty meaningless, you need to give the gravity as well.
What is really important is the amount of extract you got from the grain. 15L of wort with an SG of 1.067 is the same as 20L of 1.050, just with 5L less water.
Some rough rules of thumb that might help: -
The grain will take out about 0.8-0.9L/Kg, so if your grain bill was 4.5kg you would expect something like 3.8kg of your starting water to be taken out with the expended malt.
You should boil off something like 10% of what is in the kettle at the start of the boil. If you started with 27L, by the end of the mash and after you pull the bag, you would expect there to be 27-3.8=23.2L. All things being equal a bit more will evaporate during the mash so call it around 23L. You want to boil off about 10% so 2.3L leaving ~20.7 in the kettle at the end of the boil.

Depending on how you got your hot wort from the kettle to the no-chill cube. It is way better to leave the hot break and hop debris (collectively called Trub) in the kettle. Fitting a tap to the kettle or syphoning the wort are the best options. Pretty standard to leave around 5-10% of the kettle volume behind, with a good kettle fining and whirlpool you can get this down to a couple of percent (~2% with care).
The cold break that forms in the cube as the wort cools isn't a problem for the ferment, the hot break is best kept away from the cooling wort, then you can just empty the cooled wort into the fermenter with out fluffing around trying to filter the wort.
On filtering Break material it's really hard to filter, its a sort of jelly like substance tends to block up fabric filters or break up and go through them, either way whirlpooling in the kettle is better.

Check your gravity and dilute to match your target OG, looks to me like you might have boiled way too vigorously and just concentrated the wort too much.
Mark
 
Hi Mark,

Thanks for the feedback. My OG was 1.057, not far off the expected 1.060. I kept a close eye on the boil knowing that a vigorous boil can concentrate the wort, and I didn't think it was too vigorous. I will take more notice of the volumes throughout the process for my next batch to see where things may have gone astray.

Anyway, I shall see what the next brew brings.

Cheers,
Andrew
 

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