Oct 202225Tue

Started Geronimo II

SG 1.050 30℃ started trubinator

Great brew day today! Following a discussion with Brewfather’s creator I decided to increase the Grain Absorption Ratio in my equipment profile from the preset 0.8 to 1.2 in order to tame my mash losses, and now my volumes are bang-on where they should be. The extra water is added to the sparge amount, and when my initial increase to 1.0 only added around one litre I decided to up it to 1.2. Here’s how that compares to my previous go at this brew:

Geronimo 1Geronimo 2
Grain Absorption Ratio0.81.2
Mash Water2222
Sparge / HLT9.71 / 11.4111.71 / 13.41
Total Water33.4135.41
Mash Volume25.3525.35
GAR impact comparison table

The upshot of this change was that for the first time my pre-boil volume was on track at 28.9 litres versus expected 28.86, my post-boil volume was over by an identical 40 ml, and mash efficiency was up an astonishing 11 points at 93%.

The only fly in the ointment today (there had to be one) was that I made an inventory error when buying ingredients and found myself slightly short of hops, so I had to do a little bit of jiggling.

I don’t think this will ruin the brew but I was hoping to do a like-for-like one the hops and grains so that I can test the effects of substituting my last used Kveik for a sachet of Omega Hornindal and fermenting at 30℃ in order to tease out some of the supposedly fantastic flavours. As it stands any difference between the two brews will now be down to hops as well as yeast, which means I’ll have to do another one a few weeks down the line. Oh the hardship!

Finally, a positive discovery: dropping the Trubinator in upside-down, i.e. with the rubber on top, provides a better seal against the base of the kettle, since the metal edge is 100% flat whereas I can never seem to get the rubber to fully seal, leading to trub leaking out under the sieve instead of getting caught. Maybe this is how you’re supposed to use the device (must admit I never checked the instructions) but it would feel a bit wrong to drop it in during boil and have steel clattering on steel. I say ‘would’ because this only occurred to me during cleaning, so maybe I’ll do some research into the correct method.

Brew Day Notes

0618 Start dough-in, 22 litres mash water

0626 Dough-in finished, some prodding. 27 litres in the mash tun.

0646 Mash rest done, still at 27 litres. First stir done and now it’s 27.5 litres in there.

0650 Start mashing, stuck almost immediately. Stir. Maybe next time mix the grist better, or even bias larger grains towards the bottom?

0806 Mash-out done, tun at 75℃ and 25.9 litres. 

0812 Malt pipe raised, starting sparge. We’re aiming for pre-boil volume of 28.86 litres.

0821 Sparge done, dripping for a bit with heaters to 90℃ in preparation for boil.

0830 Dripped more or less dry, looks like 28.9 litres in there. Whoooo!!!

0855 Pre-boil gravity 1.050 (1.022 @ 80℃) against predicted 1.044 – a clear 6 points up and heading for 5.9% ABV. Too high!

0912 Boil tracker started, 60 minute additions in.

10:00 About to drop in the 15 minute additions, level before is 27.25 litres. Trubinator and chiller cut in, levels now read 26.5 litres. Expected post-boil kettle volume is 26.46, so once again I’m more or less bang-on. Result!! Heaters to max for boil, temperature 96.4℃. Resume timer now (1005) rather than waiting for rolling boil – I’m not sure I want the extra bittering of the 60 minute additions.

1015 5 minute additions in. 

1020 End of boil, start chilling to 90℃ for hop-stand.

1025 Target reached, additions in. Start hop-stand. We’re now at 26 litres, so I’m recording the previous value in Brewfather as that was with the kettle hot, not at 90℃. Gravity 1.056 (1.030 @ 76.3℃) against expected 1.048, now tracking 5.8% ABV.

1055 Hop-stand finished, starting chill.

1105 Return temperature now at 30℃, setting up for transfer.

1115 Starting transfer.

1135 Transfer finished. 20 litres shown in the fermenter including drippings from the chiller coil, could have had maybe another litre from the kettle but it would be mostly trub. SG 1.051 (1.050 @ 26℃) against target 1.048. Topping up with two litres of flat San Pelegrino, OG 1.050 (1.049 @ 26℃), should end up as 5.4% ABV.

1150 Pitching whole sachet of Omega Hornindal, adding red Tilt.

1245 Clean-up finished. There’s some bubbling from the blow-off tube already but I expect that’s due to the brew being gently warmed to 30℃ via the heat mat from an indicated 26℃.