Stepped Fermentation Schedule
This is the first time I’m following a fermentation schedule which increases in temperature towards the end, presumably to aid the yeast in providing a clean finish. Adjusting the temperature has been very easy; just set a reminder on the relevant days and then make a simple adjustment using the Inkbird app, but it’s the impact on fermentation that’s got me puzzled, because things seem to have slowed down just as I started ramping the temperature up.
My fear is that the change in temperature has somehow flummoxed the yeast and caused it to suspend operations, although most of the Krausen and foam have disappeared instead of stopping dead. There’s still a few tiny bubbles rising up from the Fermzilla’s collection jar, which seems to be half-full of good looking yeast.
Then again …
It might just be the readings from my Tilt. At the start of this brew I noticed that the device was reading 11 points lower than my old-fashioned hydrometer, so I did something that I hadn’t done before and specified an 11 point offset within Brewfather, knowing that this may well give me false readings later on because I’d previously noticed that the margin of error seemed greater at the OG end than FG.
For example, Yeti’s actual OG was 1.073 and Tilt reported 1.058 – 15 points low – but the actual FG of 1.016 is just 4 points above Tilt’s 1.012.
If we apply the same 11 point adjustment to Tilt’s current reading for Sarka, 1.020, we’re actually looking at 1.009, which is exactly where Brewfather said we should be right now and explains the levelling out of the fermentation curve perfectly.
Following this recipe has me doing yet another new thing: adding some Polyclar 730 in order to take care of chill haze, which I believe is caused by the interaction of proteins from the wort with enzymes in the hops. Polyclar’s instructions recommend that a dose between 5-25g per litre be added to secondary fermentation, but because I’m not doing a secondary fermentation I’ll be adding it at the end of primary, just before cold-crashing.
The addition process should be interesting too. I don’t need to dump any trub and I’m not dry-hopping, so there’s really no need to de-pressurise down from my 10 PSI fermentation pressure in order to remove the collection jar. Instead I’m going to draw some wort into a purged PET bottle via the floating dip tube, which will already contain the correct amount of finings in an oxygen-free atmosphere. I’ll give this a shake to mix things up before sending it back into the Fermzilla via the dip tube.
Truth be told I’m not 100% happy with using the dip tube for this purpose, but it’s the only way of doing it without risking oxidation because I didn’t fit carbonation caps to the collection jar. There’s still a couple of days to go until I need to start cold-crashing, so I’ll mull it over, but will probably go with the plan as described just now.
The one thing I do know is that, according to the things I’ve read, Polyclar is made up up plastic micro-beads so I’ll have to find a way of making sure the trub at the end of this brew goes to the incinerator and not into the environment. I only discovered this when researching how to use the product, and probably wouldn’t have bought it had I know about its composition earlier.