Tag Archives: cold-crashing

Feb 202321Tue

Fermentation seems to have stopped a couple of days ago so I’m increasing the temperature by a couple of degrees and then cold-crashing. It’s interesting to note how the yeast stopped working near the end, with the brew cooling on its own accord instead of triggering the fermentation fridge. Letting it sit for a few days and will keg later this week.

Dec 202211Sun

With a starting temperature of 34℃ I don’t want to place the chiller under too much strain, so I’ve left the fridge door and the brewery window open for a day now in order to drop some of the heat naturally. Pressure has been allowed to build to 15 PSI in preparation for chilling, all’s going well.

Nov 202203Thu

It’s unusually warm at nearly 30℃ so may take a while to get down, and I’m wondering if there’s any danger to the equipment on account of such a large drop. Glycol chillers do have a maximum chill threshold, hopefully this won’t knacker my fermentation fridge. Inkbird set for 1℃ at 13:00.

Sep 202224Sat

There’s one more day to run on dry-hop but it’s not as if we’ll reach 1℃ for a good few hours yet, so I’m setting the Inkbird now. Hop utilisation will be much slower at low temperature so I don’t think one or two days extra hop exposure will hurt.

May 202228Sat

It’s been two days since dry-hopping, so last night I tweaked the spunding valve up to 12 PSI for some extra leeway and this morning I set the Inkbird for 1℃. I expect we’ll drop to around 8℃ / 5 PSI throughout the course of the day.

Apr 202214Thu

The pressure has built back up to 15 PSI since I dry hopped 2 days ago and there’s still the odd bubble in the blow-off bottle, but if I don’t crash this now then I won’t have time to bottle it before going on holiday. Ideally I would have given the yeast a few more days to do its thing, but such is life. Can’t wait to see what this one tastes like!

Mar 202206Sun

I know I’m a good 9 days early here, but fermentation has been flat-lining here for 2.5 days and I don’t think it’s going to go anywhere, so I’m cold-crashing now and will bottle it after it’s been chilled for 24 hours. We’re away on a trip next week and it’s a case of do this now or have the apparently finished brew sit on dead yeast for another seven days, so let’s take a punt and hope that 24 hours is enough to draw out anything still floating about. Bag-thing fitted, Inkbird set for 1.0℃.

Feb 202201Tue

Things have been going pretty well since I started this brew 11 days ago, and I’ve not posted as many notes or pictures as with previous brews, partly because I’m more confident now that I’ve got 15 under my belt, partly because it’s all gone to plan.

Slow Start

That said, it did take almost 24 hours for the yeast starter to begin doing its thing, which makes me wonder if I’m doing something wrong there, or if making a starter is superfluous. Pretty much all dry yeast manufacturers recommend dry-pitching straight from the packet, and pretty much all seasoned brewers advocate the creation of a starter instead. Brewfather sides with the latter, recommending several packets of yeast if dry-pitching into a 23 litre FV, yet the vendor reckons one packet is enough. I can’t really comment since I’m still quite green, and running a parallel test is out as I still only have one fermentation fridge. I might try dry pitching next time around, but that’s likely to introduce a certain amount of variance thanks to age of ingredients among other factors.

A dose of … Meatballs?

I don’t know if it’s the use of Polyclar together with Protafloc or something else, but the protein / snot that was transferred from the kettle has clumped together to form mobile lumps which look a little like meatballs. These were quite lively throughout fermentation and have now settled down. Most strange.

Started Cold-Crashing

According to the Brewfather app I was due to drop the temperature down yesterday, but the SG curve appeared to be declining still so I left it another 12 hours. Visually there’s nothing going on in the FV now and the curve seems to be levelling out, so I’m setting the Inkbird for 1℃ and will leave it there for at least 4 days before I transfer this to a keg for lagering. About a week before we’re due to take this to a friend’s party I’ll transfer to smaller party-size kegs, ideally leaving the settled trub behind and giving us a better shot at getting it into a fridge.

2022-01 Sarka, 11 days into Primary
Dec 202123Thu

Been three days since I dry-hopped this one, time to see if we can clear things up a bit. Interestingly enough the SG has gone up to 1.006 from 1.004 according to Tilt, but I’m not concerned by the ‘loss’ in ABV as measured via this method. Pressure right now reads 14 PSI on the spunding valve so I’ll be curious to see what it drops to – guessing around 5 PSI over 5 days. Inkbird now set for 1℃, fridge humming contentedly.

Later …

It took almost exactly 24 hours to drop the temperature from 18.8℃ to 1.0℃, during which time we also went from 14 to 6 PSI. Good to know.

Nov 202127Sat
2021-11 Yeti, 9 days into Primary

This brew isn’t going anywhere else so I’m going to start crashing it now in order to be ready to keg before we go away on the 2nd, which frees up the fridge for one of the ciders – probably Allotment Riot.

It’s interesting to see a drop in temperature and then a spike over the last day or so. I think this is due to the brewery getting unnaturally cold due to some very high winds and the ventilation slit above the window being open. Room temperature is currently 13℃ and it’s been as low as 11, so I think what we’re seeing here is actually the inside of the fridge dropping low enough to engage the heater. Crazy weather!

Nov 202106Sat

No idea of the gravity (pushed for time today) but there’s been no airlock activity of late so it’s probably time to see if we can get this cleared and put away. Shoved it in the fermentation fridge as soon as Sarka came out, dialled in at 1℃.

Aug 202120Fri

This one’s now had 14 days of fermentation and it looks like we’re not going past 8.0% ABV, which is OK by me. I was going to start kegging this today but in hindsight I’m going to cold-crash it until Monday instead, then put it away.

2021-08 Yeti, 14 days into Primary and started cold-crashing

Jul 202112Mon

It’s time to start cold-crashing Sarka today, so I took the opportunity to add some Polyclar 730 in order to try and prevent chill-haze later on by dropping out all those protein lumps.

The procedure was pretty straight forward even though I’m fermenting at 12 PSI. Simply add 10g of Polyclar to a sanitised 1 litre PET bottle (10 – 15g advised for a 25 litre batch, I’ve just 23 litres in the Fermzilla) and then pressurise to 12 PSI, matching the FV. Connect a line between both vessels’ liquid-out posts, click a tap onto the PET bottle’s gas post, and give it a blip. The reduction in pressure in my “donkey bottle” soon had beer flowing in via the Fermzilla’s floating dip tube, and when I was 80% full I disconnected the tap, stopping the flow between both vessels.

At this point it was time to give the PET bottle a good shake in order to mix the fine Polyclar powder, but no matter how much I agitated the contents I still saw lumps floating about. Leaving it to sit for a few minutes helped, and subsequent shakes momentarily filled the PET bottle with a slightly more cloudy haze which then separated out to settle on the bottom.

Transferring the mixture back to the Fermzilla was as easy as giving the bottle a vigorous shake while applying pressure to the gas-in post, resulting in a flow of liquid back to my FV. It was all very easy, but I’m wondering how effective that Polyclar will be, given that it almost immediately started to settle in the collection jar despite some very obvious mixing as soon as it left the floating dip tube. Oh well, let’s see how she looks after a few days of cold-crashing.

Jun 202122Tue

I was supposed to start chilling this in order to clear out any suspended cloudiness three days ago on the 19th June, but Tilt’s progress graph still showed decreasing gravity by that point so I left her alone for a couple of days longer. With the curve now beginning to level out it’s time to drop the temperature. I’ll measure FG when I put it in the keg in a few days time, should be pushing nearly 7% ABV!

Jun 202104Fri


The controls were set for 2℃ approximately 24 hours ago and she’s now down to 4.8℃ and falling. Pressure has dropped from 20 to 15 PSI. At this rate she’ll spend the majority of the weekend just above freezing and get kegged on Monday.

SS Mini Bucket

I hope to have enough time to also bottle the contents of the mini bucket, assuming airlock activity has stopped by Monday. Probably won’t cold-crash this batch since she’ll have some time in the bottles to condition anyway, and I may well need the ferment fridge for my next batch.

May 202122Sat

In a rush – not much to note. Set it into the ferment fridge once Yeti stopped cold-crashing today, dialled in 4℃ with the sensor taped to the outside of the plastic bucket. Fitted Bag Thing full of CO2, reduced temperature further to 2.0℃ a little later.

May 202119Wed

I’m unsure about bottling this today as planned because there are some weird things going on with the fermentation that I’ve not seen before.

The bulk of fermentation activity seems to have slowed around 9 May to the point where there isn’t enough heat being produced to trip the ferment fridge into action, and temperature has been fluctuating gently very near to room temperature, which for the most part was around 19℃.

Yeti Imperial Stout, 15 days into Primary

Then something happened on 17 May which caused a sufficient temperature increase to trigger the cooler, which was set at 19℃ with a 1℃ ± threshold, so cooling starts at 20 and heating starts at 18℃. The gravity has also been bouncing up and down since then but I suspect that’s more due to the variations in temperature.

The question is, what’s causing the temperature to rise and trigger the cooler, three times in two days? There’s also some occasional airlock activity each time I open the door, as if fermentation is still underway. I can’t believe that’s the case after such a long period of stable gravity, and I don’t want to leave it too much longer, basically because I want to use my fridge for another brew, so I’m hoping that the worst-case scenario is over-carbonated beer and not an infection of some kind.

Having taken a gravity sample just now (and naturally a cheeky taste) I’m fairly confident there’s no infection – in fact it tastes bloomin’ lovely! Gravity looks to be 1.016 which makes for 7.5% ABV. Not quite the 9.7% I was hoping for, but still fairly respectable.

Instead of bottling it today I’m going to cold-crash it for a couple of days, just to see what I can convince to drop out. Bag Thing fitted, dials set to 4℃.

May 202102Sun

This brew was originally started as a low-cost experiment to see if I could do something with WLP001yeast harvested from Twisty Listy, and judging by the way it’s been fermenting these past 13 days that seems to have worked well, so now my thoughts turn to the next steps.

I’ve decided to split the batch, and dry-hop one half the traditional way in a regular bucket as opposed to a conical so as to get maximum exposure to the hop pellets instead of compacting them into small footprint. The other half will be exposed to the HFR method, or Hot French Randall. More on that later.

First it’s time to cold-crash so that I can get virtually all the yeast to drop out, and I’m doing this for two reasons; I want to harvest the yeast so that I can try this particular strain of WLP001 a third time, and I want the half of the experiment which will be traditionally cold-crashed to have as little yeast as possible. I heard somewhere that yeast interacts with the hops in a negative way (not just by venting hop oils along with any CO2 produced) and I haven’t tried it this way around before, so it’s worth a shot.

Having racked from the SS Brewtech conical bucket to a regular plastic bucket I fitted it with Bag Thing (recently revived with some duct tape after the tube came loose) and put her in the brew fridge, Inkbird set at 4 ℃. Meanwhile I used the turkey baster to remove the last dregs of beer from between the conical’s dip tube and the top of the yeast cake, before spooning some gorgeous, clean yeast into a sanitised glass jar, previously home to 453g of Manx honey. The jar filled in no time and there were probably another two jars left behind in the fermenter, which is pretty amazing considering that I originally received this yeast as two sachets of mayonnaise and had already used that to brew 22 litres of amazing IPA. If only hops could be persuaded to reproduce like that …

A final note on the state of the brew so far, and I must say that I was surprised at the darkness and the clarity, if to the aroma. There’s a definite umami quality to the nose, something between nuttiness and yeastiness, as well as a thin film that stays behind when the beer is swirled in a glass. I’m putting this down to the simply ridiculous amount of yeast that was in the bottom of the FV – over 3 lb – and I’m tempted to say that the yeast may not have fully finished clearing up after itself. I’ve had the filminess (and, to a lesser degree, the yeasty taste) in other brews which turned out fine, so I’m not worried. Cold-crashing will do its thing, and the hops are sure to mask whatever’s left over.

In terms of alcohol, in 13 days we’ve gone from 1.045 to 1.012 which equates to 4.3% ABV against Brewfather’s expected 5.0%, so not quite there yet. Those values are as measured using my traditional hydrometer – if we go by Tilt then we’re looking at 1.007 from 1.041, giving 4.5%. Also a bit short of the mark. Should I have left this in the FV longer? According to recipe I was supposed to dry-hop yesterday but we had a late night on the shooting range, and besides, I wanted to try cold-crashing and harvesting that yeast, so I figured an extra day wouldn’t have hurt. Going forward maybe I should have taken a manual gravity sample and based on the outcome waited a bit longer, but hey, it’s a learning curve.

After giving her a couple of days in the cold (aiming for 4 ℃) I’ll split the batch for traditional dry-hopping and HFR, with each half filling a 5 litre keg and, hopefully, around 10 x 500 ml bottles.

Apr 202106Tue

We’re back at 1.014 as we were six days ago despite the occasional emission from the airlock, and the sample from the trial jar is lovely. If the escaping CO2 isn’t going to lower the final gravity then I’ll be damned if I’m letting it rob me of hop goodness, so let’s get this is in the chiller and drop out some of that annoying cloudiness.

I wanted to include my new thermometer’s remote sensor by sanitising it and using it into the beer via the same stopper that’s connecting Bag Thing, but can’t count on that being a really good seal so I’ll just have to wait until I add a proper thermowell to the SS Mini Bucket.

Meanwhile I’ll see if I can get any kind of sense from the remote probe by taping it to the side of the fermenter, and insulating it from the rest of the fridge with a thick piece of foam.

Mar 202129Mon

There’s been very little movement on this brew in the past couple of days with the gravity swinging between 1.010 and 1.009, representing 98% to 100% completion against target. The only sign of life in fact has been a gradual increase in pressure since the spunding valve was closed after dry hopping 2 days ago, starting at 10 PSI and getting as far as 13 PSI today. I don’t think that’s going to cause issues with the 4 or 5 bottles (if any) that we’ll get over and above a keg, and it certainly won’t be a problem for the Cornelius.

Golden Wave Ale, 9 days into primary

The only question in my mind right now is whether cold-crashing is even necessary, since I’ve seen an unprecedented level of clarity with this, my first attempt at using Protafloc tablets. I’d be mightily pleased if a non-fined beer were this clear after a week in the chiller, so is there even any point in doing this? Well, the keg this is going into will be chilled as soon as I’ve filed it, and if chilling is only going to remove a smattering of suspended hop matter then it may as well remove it before we go to the keg.

Let’s give it a couple of days and keep an eye on the temperature via Tilt, which seems to be working just fine through the walls of the refrigerator. Speaking of which, a couple of days ago I added a gas line via the drain pipe so that I could keep my kegs carbed, and I may as well add some pressure to the Fermzilla now rather than wait until we’re in the Corny. Dialling in 15 PSI and setting the temperature control to ‘mid’ in order to prevent a repeat performance of the Great Bure Permafrost of 2021.

Mar 202110Wed

Hops were added two days ago, time to get this cleared up and put away. I filled Bag-Thing with CO2 from the currently fermenting cider in around 15 minutes (it’s going like the clappers) and swapped it for the brew bucket’s airlock before drawing a gravity sample via the sampling spigot. The bag will stay connected throughout cold-crashing so that I don’t end up sucking in oxygen as the beer cools and shrinks.

There was quite a lot of hop sediment in the trial jar which leads me to suspect that my dip tube is set too low and I’ll definitely adjust that before bottling. The gravity comes in at a smidgeon below 1.017 but I’m recording it as such because the amount of green stuff in the trial jar must surely have some impact on the reading. On the other hand, there was some slight activity in the airlock when I added the hops two days ago, which makes me think that something in the Citra has restarted fermentation.

Taste was pretty good; nowhere near as bitter as the first blonde (I’m hoping that’s the Citra in place of Cascade) and some very slight carbonation, although there was no foam at all, unlike the last sample just before dry-hopping.

The mini bucket is now inside the fridge, temperature dialled to halfway between ‘mid’ and ‘max’. I transferred what’s left of the Bure Gold to my 5 litre keg (plus half a plastic bottle) and that’s also in there. I’m hoping that the plastic bottle will serve as an early indicator of things getting too cold so that I don’t have a repeat of the day that Bure Gold started to freeze in the FV.

The only question now is when to end cold-crashing and package? With no thermometer installed in the mini keg I’ll just have to rely on best guess and maybe a sample via the rotated dip tube. Let’s look at that in a week or so, with a couple of daily check-ins to make sure that Bag-Thing still contains some CO2 to cover thermal suck-in.

Feb 202120Sat

Gravity tested at 1.011 today which means she’s only dropped 1 point in two days. That’s technically not stable yet (still producing gas from 8 PSI to 10 in 30 – 40 minutes) but it’s been 4 days since I dry-hopped and that’s already too long for my liking. The brew tastes very nice indeed, with a velvety feel and some subtle hints of citrus. At 1.011 she comes in at 4.33% ABV, which is bang-on the expected 4.3% of its official draught sibling.

Ignoring the gravity, the delay in getting this cold-crashed was down to my new refrigerator not being delivered until yesterday, and it then had to stand half a day in order for the coolant to settle. Until I make a proper shelf for the Fermzilla she’ll have to rest on some paperbacks, which isn’t ideal since it’s not 100% level and I’m concerned about transferring uneven pressure to the vessel via the stand. Seems happy enough for now.

I started the refrigerator at 15:30 and 10 minutes later the thermometer inside was already showing 13 ℃ though obviously the vessel and its contents will take longer to get anywhere near that. In preparation for the increased CO2 absorption that comes with reduced temperature I’ve increased the pressure from 10 to 15 PSI, and will check in later to make sure she stays suitably high to prevent ingress of oxygen.

Speaking of carbonation, I’ve been thinking more about the effect of temperature on the level of fizz in the beer. Using the keg carbonation calculator I see that for 2.0 vols (upper end for a British Ale) at 2.0 ℃ I should set my regulator to 5.1 PSI. If I want the same level of carbonation at 20.0 ℃ I need to dial in 19.8 PSI, and I’ve been fermenting at 10 PSI until now in order to not stress the yeast. Can we therefore assume that in order to arrive at 2.0 vols / 2.0 ℃ I now need 20 PSI and not 15? I’ll definitely check in again later in order to add some more if it looks as though I need it – can always reduce pressure easily enough once the vessel temperature has reached its target.