Bridging the carbonation gap (or the gap in my understanding!)

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FNG Brewer

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First post - keen for advice if someone can help me with what I'm not understanding.

I recently did my first batch with a pressure capable fermenter, and I've screwed up the carbonation step. I'd only done extract kits with buckets previously (30 or so batches), and only bottle conditioning. I've recently levelled up to a RAPT fermentation chamber from Kegland, and a 65L All Rounder fermenter. I had hundreds of 750mL bottles left over, and decided that I'd do some big batches and make a heap of 6 packs of beer as gifts for Christmas. Seemed like a good way of getting rid of hundreds of otherwise good bottles. I bought kegs, which I'll use when they're gone. So far, so good.

I may do all-grain later, but given that I had new toys to learn, I thought I'd start with FWK's for a while, until I understand the gear I'm using a bit better. I had no experience kegging (or carbonating in kegs), and bought a counter-pressure bottle filler for this first batch to get rid of the bottles. I opted for this NEIPA kit, and did a double batch totalling 52L. I used a profile for the RAPT Fermentation chamber that looked to be the closest thing to what I was fermenting. I followed the recipe instructions for the FWK, including the part that said "Note that if you are using a pressure capable fermenter you will get the best results at around 10-12psi. Allow pressure to build up with a spunding valve 24 hours after pitching". I kept the pressure at 12 psi during the ferment, the diacetyl rest, and the cold crash. I also noted the part that said "We would suggest carbonating and dispensing at 10-12 psi at 2°C for best results.".

There's a question coming... I promise.

Before moving to pressure fermentation, I'd read that one of the benefits was that "your beer is carbonated at the end of the fermentation.". I took that a little too literally. Keep in mind - I'd jumped from buckets / extract kits / bottle conditioning, to pressure fermentation and counter-pressure bottle filling, without the train stopping off at kegging and carbonating - so there were a few things I'd missed. I'd taken the "ferment at 10-12psi" and "we'd suggest carbonating and dispensing at 10-12psi for best results" from the recipe instructions, and the "your beer is carbonated when you're done fermenting" - and assumed that the beer was good to keg or bottle at the end of the fermentation chamber profile (ends with 2 days cold crash). Given that I was at 2 degrees at the end of the cold crash, and was already at 12psi - I assumed that I was done. Long story short - I was under carbonated.

Seems like what I've missed, is that (non-forced) carbonation takes much longer than 2 days, and that in setting my spunding valve to keep 12psi throughout the fermentation at between 18 and 24 degrees, I'd only dissolved around 1.6 volumes of CO2 before cold crashing, and that 2 days at 12psi and 2 degrees was not enough to get to to 2.4 volumes. I'd also taken that fact that there was very little foaming when using the counter-pressure bottle filler as reinforcement that I was using it correctly. It wasn't until we cracked a few bottles to try them that we found them to be flat. A bit heartbreaking to have to discard over 60 longnecks of an otherwise very tasty NEIPA - but you live and learn.

So... my question...

I have a new triple batch of Kolsch FWK (52L) going, and I've followed a slightly different temperature profile, but the same 12psi in the head space throughout. If I understand correctly, when the fermentation ends after 5-8 days at 17 degrees - I should have around 1.6 volumes of CO2 dissolved? All the online posts, blogs etc. seem to indicate that (non-forced) carbonation takes a couple of weeks? Assuming that this refers to non-pressure fermentation setups - how do I work out how much credit (in time) I get for the 1.6 volumes currently dissolved? Not in any screaming rush except that I'd like to get another triple batch in before Christmas so I can have some full kegs when family visit.

Thanks for enduring the long post. Any help appreciated.

I do pressure ferment all the time, and you need about 20psi warm that will drop down by at least 10~16 psi when beer temp is around 2 degrees Celsius, and usually needs a bit of top up from the gas bottle as well I find.
If you still have the flat batch, why not salvage them by using the Counter pressure bottle filler in reverse into a 5 litre growler or what I tend to use for a bit of overflow and temp storage is a 2 or 3L soft drink bottles with a plastic KL screw on gas/liquid red top, and pre gas it with co2, then counter pressure beer in by just cracking the seal of the top to let the gas out and the liquid in, just let it drop straight in from the top with out a tube, long as the pressure is up higher than the incoming beer, then no foam happens.
When full, tighten down your cap, place in fridge with gas attached and wait a day or 2, or speed it up by shaking it at regular intervals. Then just use it like a big long neck bottle, Darwin stubby type of thing, if you don't drink it all in one session, recap and repressurise for later.
Or you could turn it upside down with a beer line on it, probably want a KL double header cap for that though, to get gas in whilst drawing beer out.

Make sure to lower the bottle temps to about 1 or 2 degrees before opening the tops will help reduce foaming etc.
Good luck!:overhead:
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That helps indeed, Grok - thank you. Cracker of an idea to run the counter-pressure bottle filler backwards, and yes I still have 50L or so that I need to get out of the bottles before the current batch finishes - so might as well try this. I have a few empty 8L plastic kegs, so I definitely have somewhere to transfer it back to. Just couldn't imagine opening the crown seals and pouring them into kegs. Will try your method.
Your welcome, let us know if it works for you! :cheers:
Just wondering how it went for you FNG Brewer, any updates?
Just wondering how it went for you FNG Brewer, any updates?
G'day Grok,

Thanks for checking in. It worked a treat actually. I was able to use the Kegland counter pressure bottle filler exactly as you suggested, and was able to transfer the bottled goodness back into kegs - then force carbonate, and re-bottle. Surprisingly aseptic technique, and very little exchange of air. The beer was ultimately very drinkable indeed, and all of the family were well chuffed with them as X'mas gifts. I've been doing batch after batch, back to back since then and have a much better handle on carbonating now. And... I'm pretty much done bottling because all 200+ longnecks were given as gifts that we'll never see again, so box ticked there.

Am installing a draft system and under counter glycol chiller in my apartment. I have a short vacation coming up in Hobart, and am off to do the tour of Bushy Park Estates (Hop Products Australia), to learn a bit more about hops.

What's in your fermenter at the mo? Thanks again for following up, and for the great advice. Brett & Sam
Glad to hear it worked out ok!
I usually have a Brown Ale on the go these days with occasional SMASH Ale produced, just seem quiet happy with those ATM.
I find just brewing one type that I like and getting consistent results, lets me tweak the recipe little by little to fine tune it to my liking.
Would be nice to visit a hop farm, but until then I have to be content just looking at my own!
home hops.JPG
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I commonly brew at 20-25psi and 23-25degC. Which gives a cold crash pressure of 10-15psi at 2degC. This way you can littery make drinkable beer in less than a week. Proper brewers will give you a hard time that brewing under pressure (especially higher pressure like this) will ruin your beer. I don't doubt that it has an affect on the beer overall but I personally am very happy with the quality of beer I produce. I only ever make extracts due to money and time and by going to pressure fermenting and kegs the beer quality has increased tremendously and I'm more than happy.
Hi FNG, welcome to the forum and the wonderful world of pressure fermenting.

In terms of pressure fermenting in practice and the instruction you received, I've found that advice to be helpful for getting started, and is a good balance of the advantages and disadvantages of pressure fermentation. The obvious advantage of pressure fermenting is the capability to have fully carbonated beer at the end of ferment, while the disadvantage is the suppression of yeast characteristics (which again depends on your desired outcome).

Below I have attached a table and timeline I have made based on my processes. This is not the only way to achieve fully carbonated beer, but I find this strikes the best of both words where I achieve both the desired flavour profile of the yeast and fully carbonated beer.

I ferment mainly in corny kegs (with a 20mm trimmed from the dip tube), use a KL Blowtie, and a pitch volume between 11L and 16L. This is the timeline I generally follow:

DayPressureTemperatureVol C02
1 (0-24 hours) PitchNone. This stage can also be used to get the yeast actively fermenting before adding sugar/dilutions. 18C0.0
2 (24-48 hours) Transfer to keg for pressure ferment. 1PSI / 6.89kpa18C0.96
3 (48-72 hours)5PSI / 34.5kpa18C1.21
4 (72-96 hours)15PSI / 103kpa19C1.76
5 (96-120 hours)25PSI / 172kpa20C2.29

*Half turn on Blowtie raises pressure by approximately 6PSI / 41kpa
** Check gravity at Day 5 & 7. When hit desired gravity and once pressure is reached, remove spunding valve and cold crash.
*** After cold crashed for 3 days (72 hours), use tap to drain first few glasses until clear. Transfer to serving keg.

The above is based on my observations only, and in my opinion produces a far superior beer than a regular ferment that involves a transfer and force carbonation with CO2, or just a standard pressure ferment of 8-12 PSI.

In my more recent hoppy ferments, I have actually started in a plastic drum type vessel and transfer to keg with dry hops after 48 hours is reached, as this is the point where 50% of my desired final gravity has been achieved, and allows for that magical biotransformation to happen with certain yeast strains. I find the pressure is better at locking in the hop aromatics that stick around for weeks beyond what my traditional non-pressure ferments did. Dry hopping of course can be done later, but in most cases to go from zero pressure to fully carbonate beer, you will need approximately 8 gravity points remaining of your beer ferment.

I also prefer to transfer at this stage as the ferment is very active, meaning any picked up oxygen will be used by the yeast, and if I am using an ale strain that throws a big head, 50% of target fermentation gravity is a great point to top crop. The added benefit here is any break material is also left behind in the first fermentation vessel (I use no chill cubes).

Just make sure that when you hit your target final gravity and target pressure, that you remove the spunding valve before you begin your chill. With ales I find I can be drinking fresh, cold and carbonated beer within 7-9 days. With lagers I find the ferment is spend up and you can have a decent lager within 3 weeks, but I still prefer the full lagering process so drinking within approximately 5-6 weeks.
Mostly concur with Midnight Brew, but I use a stainless pressure capable 50L (46L actual liquid) fermenter and adopt the slow ramp up of pressure over days finishing around 20psi. By the time you chill that down, it still has a positive pressure, so not sure why you would remove the KL spunding valve as they behave like a non return valve anyway by the design of it. If you think it might go negative, put some CO2 in from the bottle as a top up. In fact you can leave the CO2 on at your favorite serving pressure and not worry about it.
Another plus for pressure is the ability to purge/collect yeast glug out the bottom port, even though my outlet has only a small 1/2 inch hole, if you boof up the pressure, it pushes thick yeast cake out like a big shit......;)

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