Checking in on First Scratch last thing tonight, saw there was some foam in the airlock. Thinking this was the beginnings of a delayed spew-out I removed the airlock and replaced it with a section of silicone tubing ending in a cup of sanitiser – perfect impromptu blow-off tube.
It carried on farting in brief bursts for a minute or two, then fell silent. We watched the silent seconds pass in building terror like any proud parent, until after half a tense minute or two of nothing a sudden burst filled the tube with Krausen and the beaker with froth. It’s alive … allieeeeveh!! Already I’m starting to like this particular yeast, and will make an effort to save it, setting it loose on future brews like a proud shepherd ferries his flock to new pastures.
Twisty Listy has surpassed target FG of 1.008 with 5 days still to go and is presently sitting at 1.005, which will give 4.3% and pushes the limit for a session IPA in my opinion. But that’s not the main cause for concern.
No, I’m more worried about the unusual amount of Krausen that’s still hanging around. There’s been no change in the beige blanket of snotty foam in 5 days now, and I’m used to seeing it clear up when the bulk of fermentation is done, so probably around 6 April on the graph above. There’s obviously still life in the yeast because FG keeps edging lower, but I’d be more comfortable if the Krausen receded too. Not that there’s anything I can do at this stage, will just have to write it off to a learning experience using this new style of yeast.
The temperature has been increasing steadily with fermentation and sunny weather. I was hoping to keep it around 19℃ which is the optimum for the WLP001 yeast I’m using (range: 19 – 21℃) and really need to get myself a fermentation fridge so that I can control this better. This beer doesn’t really need esters and it certainly doesn’t need fusel alcohols, so I’ve no hesitation in applying some pressure to the fermentation after 24 since kick-off.
Speaking of fermentation, it’s not been a quick starter, with the first signs of life in the airlock showing maybe 4 or 5 hours after pitching both tubes of liquid yeast. I was beginning to get worried; one of the ice packs that accompanied the yeast on its voyage over to us had become punctured by something else in the box, and I had doubts whether or not the yeast had really been kept at 4℃ all the way as intended. Things did start happening that evening, and by morning there was a thin layer of foam on top, maybe ¼ inch thick, with the usual frenzied activity going on underneath.
By noon that had increased to almost an inch, and when we came back from an afternoon walk we swapped out the airlock for a spunding valve set at 10 PSI. This had a dramatic effect on the foam, which transformed into a thick Krausen over the next few hours, almost touching the vessel’s lid by evening. To save the spunding valve I decided to move it to a spare keg and then connect that to the Fermzilla with a blow-off tube, but forgot to pre-pressurise the keg and caused much of the Krausen to head straight down the tube as soon as it was connected. I removed and cleaned the tube just in case, must remember to do the same for the Fermzilla’s PRV once this is done.
It appears as though fermentation is slowing down here. Last night there was a visible reduction in the thickness of Krausen and the Tilt gravity data had flattened out over the past couple of days to the point where I thought it would stop at 90%, but this morning it’s dropped another couple of points and is now sitting at 98% done, or 5.3% ABV.
Being able to visualised this data is amazing, as is being able to see inside the Fermzilla. Krausen has now receded to a point where there’s a clearing in the middle, and there are a couple of millimetres of clear wort just beneath the surface which look similar to the clear-ish wort that was seen in the kettle after boiling. I reckon the finings are responsible in both cases.
Also amazing is the remarkable change in colour since starting this brew, which is now much lighter and has taken on a nutty hue, a bit like milky toffee. The deposits from the lower slopes of the conical have slipped into the collection jar, which is now full past the visible brim and probably past the butterfly valve. Should be useful when the time comes to remove this in order to dry-hop, but I’m going to give the yeast a chance to clean up after itself first.
Speaking of which, dry-hopping is planned for 3 days from now, and given we’re now at 98% with so much progress in the past 2 days I don’t think that’s unrealistic at all. The recipe I’m following doesn’t specify pressure fermentation, so I wonder how far we’d be along at 0 PSI?
We’ve been at what looks like High Krausen now for a couple of days, starting two or three hours after adding fermentation pressure. The data from Tilt in Brewfather looks great, and I can see that fermentation is tailing off slightly now that we’re at 4.5% ABV, 83% of our target. Not bad at all for a 3 day old brew!
When the airlock didn’t start popping immediately after I transferred the wort to the fermenter yesterday I was a tiny bit worried, and put it down to me not having rehydrated the yeast before pitching it, choosing instead to follow the manufacturers instructions and just sprinkle it on top.
This morning there was already some airlock activity to be seen, and by 10:00 we had individual bubbles linking together to make foam. It’s now lunchtime and the foam could almost be called Krausen, as the top layer is getting darker and being broken apart by lighter layers beneath to form something vaguely like the crust on a tiger roll.
There’s plenty of activity inside too, with a kind of boiling turmoil swirling around small particles of solid matter. I’m also getting good separation between what looks like sugary fluff and the clear wort. When the liquid was added to the Fermzilla yesterday this fluffy stuff, which had already started to settle out in the kettle, was mixed up again in the FV but started to sink quickly, completely filling the collection jar and starting to settle on the conical sides. Well, today that seems to have changed again, and there’s only an inch or two settled in the collection jar and a small amount on the sides of the vessel. I don’t know if the yeast is circulating the rest or if it’s compressed down in volume, but it sure is interesting. I wonder how much of this is due to the Protafloc tablet added during boil?
The real star of the show is my new Tilt hydrometer, which has been sending back temperature and gravity readings since it was dropped into the FV at start of primary yesterday. It seems there’s quite a bit of variation in wort temperature even when the ambient room temperature stays stable. My first thought was ‘must get a fermentation fridge set up’ in order to stabilise things, but to be honest I doubt very much what difference that would make on such a large thermal mass which changes temperature from the inside-out. Keep the probe outside and it wouldn’t pick up on the subtle changes happening in the FV, move it inside the vessel and the either the pump or the heater would be running constantly, trying to impart a change likely too big by the time it gets there. Need to park that thought for now before it gets complicated.
On a positive note, the Tilt clearly shows that fermentation is in progress, in fact I’m already 15% towards my goal! I plan to leave it another 24 hours and then start adding some pressure to the Fermzilla, hoping to tame any subsequent Krausen, insure against temperature rises, and begin the process of carbonation. If that brings the total fermentation time down as expected I’ll also have to bring forward the 6 day hop additions, but we can cross that bridge later. For now I’m really glad to have Tilt’s trend graphs as a point of reference.
The foam did build up again yesterday after its disappearance following the initial addition of fermentation pressure, but now it’s receded almost to nothing and the collection jar on the bottom of the vessel is full. The spunding valve isn’t hissing as much this evening as it was 12 hours ago, so I’m wondering if we’re already getting towards the end of fermentation after just 2 days? That seems impossibly quick. I’m also wondering how I’ll add the two bags of hops without letting in oxygen, and whether the jar’s full enough with trub to interfere with the butterfly valve when I come to dump it after cold-crashing.
There are still some fresh foam bubbles in the middle of the surface and I can see occasional bubbles crawling up the inside of the collection jar, so clearly the yeast is still doing its thing and I needn’t think about taking a gravity reading just yet, which I’m quite looking forward to since it should be very easy using the picnic tap. I do want to get the hops in there before the yeast stops producing CO2 altogether since that’s a partial insurance against oxygenation, though I suppose that CO2 that I bubble in via the dip tube after dry-hopping will displace any oxygen that’s inadvertently introduced since oxygen is lighter and will exit via the spunding valve. Might be worth minimising the oxygen in the hop pellets somehow.
After reading an interesting article by Scott Janish I decided to start pressure fermenting a little earlier than originally planned with this brew. Scott also thinks that pressure inhibits the release of esters and fusel flavours and makes a case for pressure fermenting right from the start, but what’s interesting here is that there’s also a suggestion that some of the hops’ oils are lost along with the CO2 in unpressurised fermentation. Keeping that hoppy goodness locked in is one of the main goals for me, so I’m wiling to gamble a little with potential loss of mouth-feel and maltiness (which my brews to date have in abundance) in return for a little more hops. I therefore decided to ditch the airlock just 24 hours into primary and fit my new spunding valve instead.
The whole process was very easy; just unscrew the cap with the airlock, fit a freshly sanitised carbonation cap, click on the spunding valve kit. Rather than letting the pressure build naturally and then knock it back, I decided to add CO2 via the dip tube allowing me to adjust the spunding valve there and then, settling on 10 PSI for now.
I did have some concern about the building Krausen getting into my shiny new valve and briefly toyed with the idea of patching the Fermzilla to a spare keg and then fitting the valve to the keg instead, but I needn’t have worried: within 30 minutes of adding pressure the Krausen has retreated significantly and continues to shrink as I write. I believe this is another expected positive side-effect of pressurised fermentation which allows brewers to get better returns from smaller vessels including Cornelius kegs, since less room is lost to head-space.
Bad news first: one of the new design lids using grommet instead of glue is leaking and needs to be replaced. There’s enough pressure to have a visible impact on the levels, but not enough to force the bubble out of the top before the gas escapes via an easier route. You can even see the levels moving slightly as the leak activates – check the video. I’ll fix this later today, using the correct drill bit to modify a fresh lid instead of fudging it with a countersunk bit because I was too lazy to look for the right tool last time.
On to the good news now, and these two vessels are going like the clappers! There was no sign of fermentation last night as we turned in about 3 hours after starting primary, but I couldn’t resist swinging by the brewery on a 01:00 loo run and was pleased to see about half an inch of foam on the Hoppy Blonde* and maybe a quarter of an inch on the Dippy one**.
When I checked in this morning I could see a generous head of Krausen on both vessels reaching almost to the top – guess I got lucky with estimating head-space. The wort inside was in obvious turmoil and couldn’t have been more animated had there been a kilowatt immersion heater jammed into the base. I don’t think I’ve ever seen such a quick start to fermentation in a kit. Is this due to me using simple extract and steeping it along with hops rather than just adding hot water, as with all the kits until now? Maybe it’s due to the extra aeration from boiling, mixing, and splitting to two FVs? Was it the soaking of the yeast for 20 minutes and mixing it in, rather than just pitching it on top, dry? Or maybe it’s due to me accidentally using just over 1g of yeast per litre because my scales are crap. Who knows. I’ve got some better scales ordered and will likely use the same approach of waking my yeast next time since it wasn’t nearly as hard to pitch that paste as I thought it would be.
* I’m thinking of adding finishing hops to the vessel which was poured last from the bucket and subsequently received most of the sediment that was in the bucket, despite giving it a good stir. The version in this FV will therefor be known as Hoppy.
Had a quick peek under the lid and that Krausen is still there, but it seems less prominent than 6 days ago. Looking at another set of instructions (via the QR code on the paperwork) they recommend bottling if it’s within 2 points of 1.012 and stable for several days, so the last reading of 1.015 wasn’t as desperately late as I first thought. I also located the missing bag of hops, so we should be good to go as soon as the foam clears a little.
Nine days in and there’s a fantastic amount of active Krausen on top of this brew which leads me to think it’s nowhere near finished, but the SG is at 1.015 and although I’m looking for stability at 1.025 or below I’ve never seen one this far below the threshold, let alone with a foamy head still in place. Will reach out to the forum for advice.
Update 9 Jan: target bottling gravity is 1.012 according to these instructions, not 1.025. Looks like I wasn’t as far gone as I thought.
The foam seems to have peaked on both of these and is starting to recede as far as I can tell from the outside of the FV. Both vessels are still bubbling along nicely every few seconds.
On the Tripel I’m just getting a hint of Krausen on top of the brew and the specks which cover the now empty head-space are a lighter colour, as though they’ve dried.
The IPA meanwhile has had some more activity in the past couple of days and also decorated its head-space nicely, but now it looks as though it’s falling back and settling as a thick layer on top of the brew.
Looks like I spoke too soon, both the Tripel and the Grapefruit IPA are well and truly fermenting! The Tripel is almost constantly popping the airlock, maybe 3 or 4 seconds between rapports, and the IPA not far behind with 4 – 6 seconds between emissions.
The IPA has evidence of some foam touching the inside of the FV lid, and there’s a slight trace of bubbliness in the airlock, but no residue. The real star performer is the Tripel, which has managed to climb all the way up the side of the bucket and touched the lid, despite being only a third filled. Can’t imagine what this would have looked like in a 10 litre FV – probably time for a new carpet. Will need to keep an eye on these two.