What I learned about on-grain and volume

[NormandieStill]

While waiting for my new 32L buckets to arrive, I've been fermenting in my 20L ones that I got for wine + beer making. I'm playing around with a wheat + oats + enzyme mash as a way of making vodka. My first attempt used about 4.7kg of grain for 15L of water and that fitted into a 20L bucket with a tiny puke into the airlock on the first day.

But as my wheat comes in 25kg sacks I figured I should scale up to 5kg of wheat and my 500g of oats. Mashed in, cooled it, poured into the bucket and pitched yeast. 2 days later I glance at the bucket and notice that there's a little trickle of juice coming out of the grommet where the airlock is fitted. Then I realise that the airlock is full of coloured liquid. Then I notice that the lid is domed somewhat and resists being pushed down. And while trying to push it down I realise that the bottom is domed as well.

It's now sat in one of my original 30L buckets that I try to avoid using as they have a cutout for tap which only ever seems to seal after leaking a small amount of wort onto the wooden floor!

Lesson learnt. 2.5cm of head space is not enough for an on-grain ferment.

[greggn]

Then I realise that the airlock is full of coloured liquid.

For those who do closed ferments, I highly recommend changing from bubbler-style airlocks to blow-off tubes. I run a 3/4" hose into a jug with a water-clorox mixture. Aggressive ferments may push into the hose but it's never been blocked.

... and the ferment aroma is scrubbed clean by the chlorine giving my room the slight smell of an indoor pool.

[still_stirrin]

Wise advice gregg.

I learned that trick when I brewed at the local brewery. A 7 bbl ferment of beer pushes a lot of CO2, so a hose into a bucket of dilute Chlorox helped keep things sanitary smelling.
ss