Unitank users, please advise

[Jtvann]

I'm new to fermenting under pressure. I have a spunding valve coming with my setup. Should I use a regular blow off hose like normal and not ferment under any pressure until the blow off phase passes (2 days) then dial up a specific amount, or should I ferment the entire time under a specific pressure.

I've heard of CO2 coming out of solution and going volcano during dry hopping for some reason. What causes this and suggest can I do to avoid it.

I would like to harvest my yeast. When making heavily hopped beers, I assume I'd want to harvest yeast before dry hopping. Do I cold crash, harvest yeast, raise temp, then dry hop ... or how do I do it.

Should I worry about dumping trub at all. I dont want to be one of those idiots who pours out 3 gallons of good beer for a pint of trub. If I should dump it, when would be a good time?

 

[Jtvann]

Nobody huh?

 

[mongoose33]

I can only tell you what I do, and raise a question or two.

Why do you want to ferment under pressure? What are you hoping for?

*****

I have a Spike CF10. Typically I do 5-gallon batches though I've done a few 10-gallon batches. Usually I will let the CO2 come out of the fermenter through the pressure manifold. Some use a blowoff cane to do that, but I attach a QD to the pressure manifold's gas post, run a tube to a jar w/ Star-San, and use that as my airlock. I can monitor fermentation pretty well just by watching the bubbling.

When the bubbling slows, that usually is consistent with the krausen falling, and when that does (in the case of ales), I'll bump up the temp to let the yeast finish.

Now, that's a normal fermentation. More recently, I've been closing up the fermenter (i.e., sealing it, by removing the QD on the gas post) when there is about 5-7 points of gravity remaining. Depends on whether it's a 5- or 10 gallon batch. With a 5-gallon batch, because there's so much more headspace, I'll do 7 points.

This is spunding.

In essence, what I am doing is "bottle conditioning" in the unitank. Carbonating naturally, in other words. I can err on the side of a few more points of gravity as the PRV on the unitank won't allow more than about 13 psi.

When finished, I have about 1.5 volumes of CO2 in the beer. Not enough, usually, as I'm aiming for about 2.5 volumes, but that's completed after I rack to keg and put it on the gas.

The hard part with all this is knowing how many points one has remaining. One way is to pull samples off the unitank to monitor. Another way is to use something like a Tilt hydrometer to keep track. I have a Tilt, but the performance is more uneven than I'd like. That's why I like to monitor the bubbling through the airlock jar, it helps confirm when it's time to seal up the fermenter.

I don't dump trub; could, but I haven't seen a reason. Mostly that's because I rarely have beer in the unitank for more than 2 weeks.

*****
As far as hopping....when you add hops to beer that has CO2 in it--and it will--the hops provide nucleation points and thus bubbling and foam. Sealing the unitank after adding the hops should solve that problem.

 

[6Tap]

Well..... not sure if this is right or wrong, but I ferment in my conical, then once done, drop the temp down to 50 degrees and harvest yeast, then dry hop for 4 days, then cold crash and add gelatin once it hits 33 degrees and keep on 5psi of co2 for 2 days while cold crashing until I keg. Seems to work well.
Beer has some co2 already in it once keged and usually only takes 1 more day at 35psi of co2 40 degrees f to be close to fully carbonated.

Oh yea, if your beer has a lot of dry hops
I recommend you drop some out the bottom before keging, and once your cold crash is done.

Cheers [emoji482]

 

[jaymosbeershack]

I have a process similar to mongoose. If i am looking for a really clean fermented beer, i will put it under 5-7 psi about 24 hours after i can see evidence of fermentation (bubbles from the blow off tube.) Fermenting under pressure can suppress yeast expression. As far as trub dumps go, if its heavily dry hopped, ill do a dump or 2 to get rid of the dry hops, otherwise i havent found it to be needed.

 

[Qhrumphf]

Dry hopping carbed beer (even partially) through the top can result in a catastropic geyser. Almost every pro brewer has had it happen (even just residual CO2 from fermentation is potentially enough). This is because the hops create nucleation sites allowing all the CO2 to come out, fast.
It seems to get worse with scale (observation, no hard data, I assume it's because hops don't get bigger even though the batch size does, so the increased amount of same size pellers and inherent relative surface area increase speeds the reaction). I've never seen/experienced a homebrew scale geyser, but I've also never tried dry hopping carbonated beer without using special techniques.


I do everything by gravity. Allow it to blowoff like normal until you're 4 points above your target. Then close it off.

If you're not dry hopping, it can be left as is. If you're dry hopping, either set a spunding valve to zero or burp off pressure a few times a day, until it's done.

Some will soft crash when capping/spunding (set to lower 50s), and then harvest when it's done. I'm partial to English yeast even for American styles and find this route problematic. But it allows you to harvest as soon as it's done and get lots of clean yeast, and then dry hopping at that temp is beneficial as well.

I prefer to leave it at ferm temp or raise a degree or two and then harvest and dry hop at ferm temp.

Although ultimately with hop creep being a risk, unless I absolutely need that yeast I prefer to dry hop *when* capping it off so the yeast are still active to quickly metabolize any hop creep products. I just won't harvest dry hopped beers.

Your other option is dry hopping under pressure. This is difficult to do at home. Though there's a thread on here on no-oxygen dry hopping with ideas that could work.

 

[Vale71]

Your other option is dry hopping under pressure. This is difficult to do at home. Though there's a thread on here on no-oxygen dry hopping with ideas that could work.

And here it is.

 

[Jtvann]

Thanks for the replies. This is my first time using my unitank, so let me know if this seems reasonable.

I set my sounding valve really low, to like 2 psi from the start. If its holding pressure, then I know for sure there's no oxygen coming in.

I'll let it ferment out until bubbles slow, also monitoring with a tilt to see when it's close to being done. At that point I figured I'd do it all, dump trub in order to harvest some good yeast and dry hop too.

I'm wondering about the soft cold crash part. If I drop the temp to about 50 to make the yeast settle for harvesting, won't the temp drop potentially halt fermentation.

I'd like to cap off under pressure to naturally carb up the last few pts. I can go up to 30 psi on the unitank, but I think I'd rather stay <25 just for safety sake

 

[Qhrumphf]

I'm wondering about the soft cold crash part. If I drop the temp to about 50 to make the yeast settle for harvesting, won't the temp drop potentially halt fermentation.

Greatly depends on your strain. Workhorse strains like Chico handle it just fine.

Other strains that are more temp sensitive it can be an issue. Many Belgian brewers do this, and I've seen it work with a few Belgian strains.

Where I encounter issues is with high flocc low attenuating English yeasts (my preferred for US and UK styles alike)- then you can drop the yeast too early/fast and leave an underattenuated diacetyl bomb. So not my normal route, I instead raise the temp 2F when capping it off.

May take some experimentation to see what works best with your yeast(s) of choice.

 

[Jtvann]

Yeah, I had wanted to try to do it all with my first batch. I'm using safale 05 for this batch just as an experiment. I'm not too concerned about harvesting it for reuse, more just for the practice of doing it for other yeasts. My goal was to be able to:

1- Ferment under pressure (2 psi or so)
2- Spund and naturally carbonate
3- Dry Hop
4- Harvest yeast

Sounds like I may not be able to do all 4 things in the same batch. I think my plan at this point is to ride out fermentation to the very end with stable gravity for 2 days ... probably day 6ish. Soft crash to 50 and harvest yeast, then immediately dry hop. I'll dry hop 4 days at whatever temp it free rises to. Will then cold crash down to 35 for 2 days while adding CO2 through the carbonation stone, following the chart for my pressure.

My plan is to keg 5 gallons and then bottle the rest directly from the unitank. I aimed for a 11 gallon batch. Wasnt sure how much loss I'd have from dry hops etc.

 

[NeoBrew]

I've get several batches under my belt with a unitank now. Another issue to look out for is that transferring to a keg with carbonation can create extra troubles as well. Between foaming and having poppets get stuck due to hop debris rising with carbonation in the unitank I've decided that I'm going to wait to carb in the tank until I get some of the other things like yeast harvesting and dry hopping worked out.

 

[Qhrumphf]

Foaming issues when kegging carbonated beer is easily solved by keeping the keg under pressure. Keep keg at (or some prefer slighly above) your equilibrium carb pressure, and increase head pressure in the tank a few PSI above that.

 

[NeoBrew]

Foaming issues when kegging carbonated beer is easily solved by keeping the keg under pressure. Keep keg at (or some prefer slighly above) your equilibrium carb pressure, and increase head pressure in the tank a few PSI above that.

What do you use to keep the keg "slightly above your equilibrium carb pressure"? Would it take a spunding type pressure relief valve on the keg? I've don't find it that easy to simply let out the pressure on the keg in a even manner by using either the pressure relief valve or holding down the poppet.

 

[mongoose33]

What do you use to keep the keg "slightly above your equilibrium carb pressure"? Would it take a spunding type pressure relief valve on the keg? I've don't find it that easy to simply let out the pressure on the keg in a even manner by using either the pressure relief valve or holding down the poppet.

I think what @Qhrumphf means is to keep the keg at the pressure of your beer, i.e., if you have the beer carbed to 11 psi, then that's what you set the spunding valve at, and you use something like 13psi in the unitank to push it to the keg.

 

[Qhrumphf]

What do you use to keep the keg "slightly above your equilibrium carb pressure"? Would it take a spunding type pressure relief valve on the keg? I've don't find it that easy to simply let out the pressure on the keg in a even manner by using either the pressure relief valve or holding down the poppet.

A spunding valve is gonna be the best way to keep it consistent, yes.

 

[sensei247]

Yeah, I had wanted to try to do it all with my first batch. I'm using safale 05 for this batch just as an experiment. I'm not too concerned about harvesting it for reuse, more just for the practice of doing it for other yeasts. My goal was to be able to:

1- Ferment under pressure (2 psi or so)
2- Spund and naturally carbonate
3- Dry Hop
4- Harvest yeast

Sounds like I may not be able to do all 4 things in the same batch. I think my plan at this point is to ride out fermentation to the very end with stable gravity for 2 days ... probably day 6ish. Soft crash to 50 and harvest yeast, then immediately dry hop. I'll dry hop 4 days at whatever temp it free rises to. Will then cold crash down to 35 for 2 days while adding CO2 through the carbonation stone, following the chart for my pressure.

My plan is to keg 5 gallons and then bottle the rest directly from the unitank. I aimed for a 11 gallon batch. Wasnt sure how much loss I'd have from dry hops etc.

How has this worked out for you? Looking at doing similar but using a sight glass to purge hops and butterfly TC to drop into unitank

 

[Jtvann]

Had to go back and reread my post. Kinda old. It’s funny to go back and read some of the stupid things you used to say.

Don’t ferment ales under pressure, it suppresses flavor that you’re probably looking for.

When I dry hop, I just take off the PRV and drop them in. I’ve got a 22oz dry hopped neipa that still tastes great 4 months later. Can’t pick up any oxidation.

You need to harvest yeast before pressurizing. Yeast will absorb CO2 if not. It will become a mess dumping carbonated yeast.

You need yeast to be active to carbonate. They don’t have to be super active, but some activity is required.

You need yeast to be finished fermenting before harvesting. Too early and you just picked the ones who quit early affecting future batches.

You need to harvest before dry hopping. Unless you want your subsequent beers to be hoppy.

These are all my opinion, and subject to someone else’s disapproval. If I could update my old post.

1- don’t ferment ales under pressure, there’s no need.
2-Spunding is fine, I do it most of the time. I pick wether to harvest or spund though. I don’t do both.
3- Dry hopping is a lot easier than it’s made out to be here. I go back to what breweries do. If a brewery is making a neipa, do that put their hops in a canister or just dump them in. I’ve seen them just dumped in.
4- Harvest yeast is fine. It easier to do if you wait a long time, don’t ferment under pressure and don’t dry hop. Add any of those 3 things and it’s doesn’t make it impossible, but harder. Add all 3 and I question why you’re even doing it.

 

[sensei247]

Had to go back and reread my post. Kinda old. It’s funny to go back and read some of the stupid things you used to say.

Don’t ferment ales under pressure, it suppresses flavor that you’re probably looking for.

When I dry hop, I just take off the PRV and drop them in. I’ve got a 22oz dry hopped neipa that still tastes great 4 months later. Can’t pick up any oxidation.

You need to harvest yeast before pressurizing. Yeast will absorb CO2 if not. It will become a mess dumping carbonated yeast.

You need yeast to be active to carbonate. They don’t have to be super active, but some activity is required.

You need yeast to be finished fermenting before harvesting. Too early and you just picked the ones who quit early affecting future batches.

You need to harvest before dry hopping. Unless you want your subsequent beers to be hoppy.

These are all my opinion, and subject to someone else’s disapproval. If I could update my old post.

1- don’t ferment ales under pressure, there’s no need.
2-Spunding is fine, I do it most of the time. I pick wether to harvest or spund though. I don’t do both.
3- Dry hopping is a lot easier than it’s made out to be here. I go back to what breweries do. If a brewery is making a neipa, do that put their hops in a canister or just dump them in. I’ve seen them just dumped in.
4- Harvest yeast is fine. It easier to do if you wait a long time, don’t ferment under pressure and don’t dry hop. Add any of those 3 things and it’s doesn’t make it impossible, but harder. Add all 3 and I question why you’re even doing it.

Thanks so much for all of this. Super helpful and appreciate the time you put into writing this.

One quick follow up- what is your process for spending a beer you dry hopped? or is this not possible since you need to harvest yeast before dry hopping?

 

[Jtvann]

It’s not practical to do everything. If I spund and dry hop, I don’t harvest the yeast.

Near the end of fermentation, just toss in the hops and close the valve.

You don’t want to harvest carbonated yeast. You don’t want to harvest yeast that isn’t done flocculating. If it’s done, it won’t continue to carbonate making spunding impossible.

If you do want to do everything, it won’t be natural carbonation.

You can wait till everything has finished fermenting. Cold crash to settle yeast. Harvest yeast. Dry hop, raise temp back up for dry hopping if you prefer warm dry hopping. Add CO2 by the carbonation stone. Drop temp again to crash hops. Dump hops. Continue to carbonate cold. Fill purged kegs or bottles.

That’s the process you “can” use, but I don’t follow it very often.

 

[eric19312]

You can wait till everything has finished fermenting. Cold crash to settle yeast. Harvest yeast. Dry hop, raise temp back up for dry hopping if you prefer warm dry hopping. Add CO2 by the carbonation stone. Drop temp again to crash hops. Dump hops. Continue to carbonate cold. Fill purged kegs or bottles.

THis is what I mostly do now. A few differences or maybe just missing details...
+I switch from blowoff tube to pressure manifold before the first cold crash.
+Once the pressure manifold is on there I make sure to keep at least 2-5 PSI in the headspace at all times. If the beer absorbs some of the CO2 from the headspace I add some more through the pressure manifold.
+The first cold crash to dump the yeast is a soft crash...down to 55F. Seems to do the job for ale yeast although most of my experience is with harvested and repitched Chico yeast.
+After adding the dry hops I may or may not warm the beer back up to fermentation temps.
+I cold crash and dump the hops before hooking up the carbonation stone. Carbonated hop soup is not much more fun dumping than carbonated yeast.
+++Always keep positive pressure in the headspace during crashing. The units are not designed to tolerate negative pressure and you could damage your unitank.

 

[Jtvann]

Agree on all points. I was too abbreviated.

 

[sensei247]

THis is what I mostly do now. A few differences or maybe just missing details...
+I switch from blowoff tube to pressure manifold before the first cold crash.
+Once the pressure manifold is on there I make sure to keep at least 2-5 PSI in the headspace at all times. If the beer absorbs some of the CO2 from the headspace I add some more through the pressure manifold.
+The first cold crash to dump the yeast is a soft crash...down to 55F. Seems to do the job for ale yeast although most of my experience is with harvested and repitched Chico yeast.
+After adding the dry hops I may or may not warm the beer back up to fermentation temps.
+I cold crash and dump the hops before hooking up the carbonation stone. Carbonated hop soup is not much more fun dumping than carbonated yeast.
+++Always keep positive pressure in the headspace during crashing. The units are not designed to tolerate negative pressure and you could damage your unitank.

Good points- 2 things:
1. Assuming you are NOT spending beers which have been dry hopped (no yeast left). Correct?
2. Do you have a vacuum breaker TC installed? I have thought about adding a "Y" TC extension which has both the high press (15psi) manifold PRV AND vacuum breaker for low press (I think the vacuum breaker TC blows off high press at 30psi...far too high for Spike CF conical).

Thoughts?

 

[sensei247]

It’s not practical to do everything. If I spund and dry hop, I don’t harvest the yeast.

Near the end of fermentation, just toss in the hops and close the valve.

You don’t want to harvest carbonated yeast. You don’t want to harvest yeast that isn’t done flocculating. If it’s done, it won’t continue to carbonate making spunding impossible.

If you do want to do everything, it won’t be natural carbonation.

You can wait till everything has finished fermenting. Cold crash to settle yeast. Harvest yeast. Dry hop, raise temp back up for dry hopping if you prefer warm dry hopping. Add CO2 by the carbonation stone. Drop temp again to crash hops. Dump hops. Continue to carbonate cold. Fill purged kegs or bottles.

That’s the process you “can” use, but I don’t follow it very often.

Thanks again! Makes sense.

So if I wanted to spund in keg, I could:
1. drop in hops toward end of ferm
2. let it dry hop for 2-3 days
3. Transfer via filter to keg
4. Spund beer in keg (zero oxidation)

^^During this process continue to closely watch gravity changes with respect to target final gravity and time each step accordingly (I have a Tilt so have a bit of control here). Of course will need to have enough gravity left at step 3 to spund in keg.

Thoughts?

 

[eric19312]

Good points- 2 things:
1. Assuming you are NOT spending beers which have been dry hopped (no yeast left). Correct?
2. Do you have a vacuum breaker TC installed? I have thought about adding a "Y" TC extension which has both the high press (15psi) manifold PRV AND vacuum breaker for low press (I think the vacuum breaker TC blows off high press at 30psi...far too high for Spike CF conical).

Thoughts?

I am not spunding for carbonation. I agree with previous posts -- spunding / harvesting yeast / dry hopping seem to be a challenge to do in a single beer. I'm harvesting and dry hopping and that combination is pretty easy.

I guess you could always follow yeast harvesting and dry hopping with an addition of Speise for spunding. You could crash to 55, harvest yeast, dry hop at 55. Crash to 45 and dump the hops (most of them anyway). Warm back up to 70 and add the Speise. There will still be enough yeast in suspension to ferment out the Speise for carbonation and you would also take care of any fermentables created by hop creep. Give it a few days with the Speise and then crash again as cold as you can go. At end of cold crash give it the last bit of CO2 (calculated for temperature) through a carbonation stone and next day do a closed transfer to purged kegs. Speise could be conveniently replaced with boiled corn sugar or malt extract and might be added to the fermentor pretty hot since you are bringing temps back up anyway.

 

[eric19312]

2. Do you have a vacuum breaker TC installed? I have thought about adding a "Y" TC extension which has both the high press (15psi) manifold PRV AND vacuum breaker for low press (I think the vacuum breaker TC blows off high press at 30psi...far too high for Spike CF conical).

No I'm using the Spike manifold which has a PRV set to 15 PSI and a gas connection. I put my spunding valve on the gas connection. I don't have room above for a Y but I could probably mount one via the 4" TC port since I don't use the temperature coils.