I believe I was right to attribute yesterday’s initial bubbling of the blow-tube to temperature expansion since there was no sign of foam, but this morning’s a different story, with a nice cake of healthy krausen sitting on the FV’s surface just 18 hours after pitching.
The blow-off tube is popping constantly and the spunding valve has settled on exactly 5 PSI and is hissing quietly. I’m wondering if 5 PSI is enough to suppress some of the yeast’s desired character so maybe we’ll try one without pressure at some point, but for now I like the head start on carbonisation and prevention of O2 ingress during cold-crashing.
It’s 21:15, about eight or nine hours since pitching, and this Kveik has just taken off in the last hour or so. I’m seeing a growing carpet of foam on top of the wort and have fitted a blow-off bottle, moving the spunding valve away from the likely erupting Krausen.
I’ve set the spunding valve to 10 PSI by dialling it high and filling the blow-off bottle from my CO2 tank, then reconnecting the valve and opening it until the pressure dropped back down to 10. Unfortunately I didn’t de-pressurise the bottle further, and when I reconnected it to the FV a small amount of sanitiser rushed up the dip tube as the vessels equalised. Hopefully that won’t trouble the wort or the yeast too much in this important early stage – oops!!