1st time pressure fermenting - Yeast stalled out already?

[timsch]

I'm fermenting a batch of Oktoberfest in my new Fermzilla All-Rounder. I pitched a WLP 820 3L starter on Saturday. Fermentation kicked off within 12 hours it appeared.

I've got the pressure kit on it and was holding pressure ~ 12 psi for a couple of days with temperature kept ~60F. Krausen was nice and the bubble cup was bubbling. The day before yesterday I noticed the pressure had dropped below 10 psi. I bumped up the fermentation temp a few degrees, but that didn't change anything. Now it's below 5 psi. There's still a healthy looking krausen, but no bubble activity in the cup. I've sprayed all connections with soap water and see no leaks, although I couldn't really test the large oring in the cap due to the retaining ring.



I'm not sure what to make of this. I'm used to not seeing bubbles due to leaks in my previous setups, so know that's not a sure sign of a problem. I'd usually smell CO2 when opening the fermenter/freezer, but don't smell that now.

Being new to pressurized fermenting, I'm sure there's some things I don't know yet. I've read that WLP 820 can be weaker than normal, but with it kicking off pretty quickly, I'd not expect it to peter out.

Is there something I might have missed that may have caused a fermentation problem?

 

[micraftbeer]

The fact that your pressure dropped (presumably without you adjusting your valve) indicates you have co2 finding an escape path. Otherwise, you'd see pressure rise to the point you have your valve set to, and then just stay there. Excess gas buildup would push out through your spunding valve. When fermentation stopped, it would just stop pushing gas out, but your gauge would stay flat at that pressure.

The fact you aren't seeing bubbles in your bubbler confirms the co2 is getting pushed out somewhere else.

So you'll have to wait it out to determine your finish point, you can't base it on bubbles in your bubbler. You can take gravity samples and wait until you get unchanged value over 3 days. Or you can just sit and wait 2 weeks.

 

[timsch]

All true. I observed the krausen longer just now and there is bubbling seen there, so definitely still active with a gas leak somewhere.

The articles I've read on pressure fermenting don't go into specifics for temperature. I read that one benefit to pressure fermenting is it can be done at a higher temperature. What are some typical temperature profiles for this type of setup?

 

[Bassman2003]

It seems your yeast is ok, but I have found pressure fermenting to require more yeast than a non-pressure ferment. The pressure tends to suppress esters which allows you to raise the temps without creating unwanted esters. For ales, I find you might want to raise the temps anyway to avoid the beer turning out too clean. Lagers are clean by nature, so you go up or down the range. I am focused on still fermenting lagers at 50F but at 15-30 PSI.

Pressure adds a lot of levers to play with. Remember, most of the commercial beers out there are fermented in large tanks that have an inherent amount of hydrostatic pressure built in. So pro brewers start at what is considered a high amount of pressure compared to home brewing. This was apparent to me after doing some pressure ferments then remembering some things pro brewers said in podcasts. Like when Mitch Steele said they fermented Stone IPA at 72F. At the time I thought that was kind of high. Now that I know he was dealing with a lot of pressure, he needed to raise the temps to get some ester formation. This same beer at the homebrew non-pressure level would probably be at 66F or 68F.

 

[micraftbeer]

Another thing to think about is the higher pressure slows down the fermentation rate. Raising the temperature increases the fermentation rate. So typically these two go hand in hand.

 

[hiphoppotamuss]

You’ve probably double checked this but I pressure ferment using that exact same system. I seem to ALWAYS get micro leaks from one or both the top two carbcap posts unless I put some PTFE tape on the threads and really screw them on tight. I know kegland says not to over tighten, but honestly it’s the only way I can keep the system from leaking.

 

[timsch]

You’ve probably double checked this but I pressure ferment using that exact same system. I seem to ALWAYS get micro leaks from one or both the top two carbcap posts unless I put some PTFE tape on the threads and really screw them on tight. I know kegland says not to over tighten, but honestly it’s the only way I can keep the system from leaking.

It looks like they have a plastic tapered ring that is supposed to seal on the cap. IIRC, someone put garden hose connection gaskets to seal. Anybody tried anything like that? I have a few assortment kits of orings that I will look into.

 

[hotbeer]

Sounds like it's been 3 or 4 days since you pitched. And actual fermentation is probably over or nearly so. So there won't be much if any CO2 generated to keep the pressure up if you have any leakage at all, which might be asking a lot. Probably not worth trying to fix the leakage now. You might ruin your beer fiddling with it.

Wait till it's all done and you have kegged or bottled it. Then try to find the leak when there is no beer in it.

 

[timsch]

Sounds like it's been 3 or 4 days since you pitched. And actual fermentation is probably over or nearly so. So there won't be much if any CO2 generated to keep the pressure up if you have any leakage at all, which might be asking a lot. Probably not worth trying to fix the leakage now. You might ruin your beer fiddling with it.

Wait till it's all done and you have kegged or bottled it. Then try to find the leak when there is no beer in it.

Yeah, it's been about a week now. Activity has slowed based on the thickness of the krausen. I did remove the cap last night to put lube on the seal. I also snugged up the plastic posts a bit. This morning the pressure had risen from atmospheric to now ~ 7-8 psi, so that's an improvement.

I didn't do a proper leak test on it before using it, so I've earned all of this. I'll do a pressure test with the cap submerged after this one is done.