Originally Posted by mtnagel
Perhaps you've already done it and in that case you can ignore this, but getting completely homogeneous mixtures of solid particles isn't the easiest thing, so I wouldn't assume that taking off 20% of it will still result in what you expect. Of course brewing isn't an exact science, so it will probably be fine, but just wanted to let you know.
Couldn't you have just increased the batch size? Of course there are reasons why you may not have wanted to that too.
Already bringing to boil, so indeed too late, but... yes and no on the increasing batch size.
Boiling down to 10.5 gallons. Moved it up to a 90 minute boil, so volume out of the tun was closer to 13.6 gallons.
My tun can certainly deal with 15 gallon batches up to about 1.075, but a 20% larger batch probably wouldn't have fit in the keggle for a 90 minute boil (16.32 gal), and it would have been very tight at 60 minute even (15.36 gal).
Plus, my fermentation chamber only has room for 20 gallons (4 buckets), and I put 10 gallons of a scotch heavy in there yesterday.