Repitching after a closed transfer - think I might have messed up big time (possibly stuck -help!)

[OzzyPeeps]

So a bit about my process. I brew large 20 gal/80l batches of either extract or partial mash.

I brew in "fermenter genius" 100l/25gal fermenters ...

They have a main lid which is like about 12 inch diameter and another little lid/port in the centre of the main lid which is like 1.5 inches ...

Up till now I've just been doing open transfers from them -

I would fill 4 un-purged cornys at an angle via the liquid dip tube and as they fill, the displaced beer in the FV is replaced with ambient air. (i.e. 21% oxygen)

On the last keg I open the main (big) lid so I can see what's going on with the cake and tilt the FV to get the dregs out ...

After dumping the slurry I start filling the tank - typically I will just tip the high grav wort in the "manhole" either directly from the kettle or using stock pots and then I top up with clean RO via transfer pump with a sparge head ensuring it is oxygenated as it is transfered - then I pitch.

But if course we are all trying to improve and refine our processes over time ...

I've been working hard at developing a zero O2 ingress/lodo strategy for these fermentors

The issue is that they are just big plastic buckets with no pressure rating and the big lids do not seal very well (small one is ok) - but what do you want for 100 bucks? (I want 4 cornies full of delicious beer!)

So having managed to get a half decent seal with a lot of f***ing about with plumbers tape and Vaseline - good enough to liquid purge kegs with ferm gas - I was ready to try to implement my new zero oxygen closed transfer.

It worked perfectly (for the beer getting packaged)

The kegs were purged and keg gas out went to FV gas in, replacing the gas in the headspace with CO2, so no oxygen ever touched the beer.

I repitched slurry from the batch just kegged and I always over pitch lagers (using nova right now gen3)

Normally i would expect it to be cracking off in a matter of a couple of hours after a repitch but this was Friday night 12 midnight Irish time and it's now Sunday 6pm - 42 hours ago - and not a sausage. Not a single bubble in the blow off -

My working theory and where I think I might have f'ed up is this:

As all of the beer in the FV was replaced by CO2 in the closed transfer, the splashing from the sparge head inside the tank as it was pumped in would only have been in contact with CO2 and therefore not getting oxygenated. (I only used the 1 inch port to get the sparge head in, as I didn't want to f with the seal on the main lid)

Think of a corny purged with CO2 - you can open the PRV and shake the **** out of it but that's not gonna get enough O2 into suspension for a healthy fermentation ..

That's my theory anyway ...

Hopefully I'm just being paranoid ...

It's novalager which I have read can lag and seem to be doing nothing but I assume that's from dry yeast and it seems like a hell of a lag.

Because of the size and weight of the tank, I can't "walk" it.

I have an air stone and a ****** aquarium pump but it's hard to even fantasize that would be enough to oxygenate that volume of wort

The only other thing I can think of is recirculating with the transfer pump but the same problem would obtain ... The sparge head would be in the headspace which is all CO2 so it would just be in a CO2 loop

Ii guess I could put my kettle above the open FV, and recirc from the FV tap through the sparge head into the kettle with the tap open so it drains back into the top of the FV ...

But obviously that's a last resort.

I'm looking for any advice from people who routinely repitch straight after a closed transfer (without cleaning FV) say in a fermzilla 55 or whatever.

There should have been a reasonable amount of O2 in the ro water as it was run open to a pot before pumping in

Also any advice from anyone with experience directly repitching novalager

How long would you wait before you start panicking?

Thanks guys ... I worked really hard on this beer so any advice welcome

If I'm honest I'm not sure how much attention I used to pay to the airlock as before it was inside the chamber and now it's out (visible)

I'd just set and forget. But with the change in process and I'm second guessing myself and getting paranoid ... It seems like an awfully long time ... Aaargh

The downside of doing big batches is if you F them up

Ozzy

Edit to add ... Thinking about it now I remember the last one done in the same tank was a repitched Vienna lager with the same yeast same amount and it was cracking off Verry quickly

It will be 48 hours from pitch in about 6hrs ... 12 midnight here

Would you try to intervene tonight or wait till tomorrow?

Is it worth waiting to see if it's just sluggish to get going vs stuck?

Thanks again

 

[IslandLizard]

Chances are your beer is fermenting fine, you just don't see any CO2 activity due to imperfect seals. IOW, CO2 simply leaking out.

To inspect the headspace for krausen, can you peek down the airlock hole in the fermenter's lid while shining a flashlight through the side?
Or just lift the lid a little.

 

[OzzyPeeps]

Impossible to say as to Krausen ... It's a repitch without cleaning the fermenter so the scum from last brew is still there to the same was l liquid line.

I looked in , of course there are bubbles on the surface but that doesn't mean it's not stuck

OG 1070 after nearly 2 days ... First time I checked the OG. Higher than I am thought it would be (obviously nailed the mash) so zero attenuation so far

 

[IslandLizard]

Impossible to say as to Krausen ... It's a repitch without cleaning the fermenter so the scum from last brew is still there to the same was l liquid line.

Do I understand correctly that:

1. You pitched your new batch of 1.070 OG onto a whole previous (NovaLager) yeast cake from a similar sized batch with a similar (~1.070) gravity?
2. You didn't aerate/oxygenate the new wort during or after pitching

If so, that yeast cake should be large enough, having plenty of active cells, to ferment your new batch.
Although 1.070 is a fairly high gravity, it's not excessive, and the yeast can handle it.

It will be 48 hours from pitch in about 6hrs ... 12 midnight here

If you are sure there has been 0 activity (no attenuation, thus no alcohol formed), you can still oxygenate/aerate.

 

[OzzyPeeps]

Would the impellers or pressure from a diaphragm pump harm the yeast if I decide to recirculate?

Kegland super sucker siphon pump is the pump 90 psi

 

[OzzyPeeps]

Do I understand correctly that:

1. You pitched your new batch of 1.070 OG onto a whole previous (NovaLager) yeast cake from a similar sized batch with a similar (~1.070) gravity?

No, I dump out the slurry, fill the tank and then pitch about 1/3 of the slurry ...

 

[OzzyPeeps]

If you are sure there has been 0 activity (no attenuation, thus no alcohol formed), you can still oxygenate/aerate.

It's the only reading I took but I don't see how OG could possibly have been Higher - I was shooting for 1060!

What if I give it till tomorrow and it has dropped a couple of points?

I'm guessing the oxidation risk is a function of attenuation?

As in the less it has attenuated the less harm done and the further on it is the riskier it gets?

What happens if it gets stuck half way through?

My only option would be to aerate ...

 

[IslandLizard]

Would the impellers or pressure from a diaphragm pump harm the yeast if I decide to recirculate?

Kegland super sucker siphon pump is the pump 90 psi

I don't know if those type of pumps are safe for yeast.

No, I dump out the slurry, fill the tank and then pitch about 1/3 of the slurry ...

When repitching on 1/3 of the old cake, the yeast is expected to grow new cells first, and thus needs oxygen/air.

I'm guessing the oxidation risk is a function of attenuation?

As in the less it has attenuated the less harm done and the further on it is the riskier it gets?

Yup, they're related.
For high gravity worts (say >1.080) a 2nd oxygenation/aeration is recommended 12-18 hours* after the first oxygenation (and pitch). Best to apply before there's been any attenuation.

* The timing varies depending on the application.

What happens if it gets stuck half way through?

You surely want to prevent that, or you'd end up with a batch of sweet beer. You could try blending that with dryer beer.
Resurrecting stalled fermentations is difficult, moreso the higher the ABV is.

My only option would be to aerate ...

That should work fine.

 

[OzzyPeeps]

When repitching on 1/3 of the old cake, the yeast is expected to grow new cells first, and thus needs oxygen/air.

I have 2/3 of the same yeast from a batch 6 weeks ago (not refrigerated but been around 5-10c)

Given that aeration would be seriously difficult if not impossible with the equipment I have, would I be better off to just pitch that in?

Or indeed pitch a new dry pack of nova just to be safe?

 

[OzzyPeeps]

I don't know if those type of pumps are safe for yeast.


When repitching on 1/3 of the old cake, the yeast is expected to grow new cells first, and thus needs oxygen/air.


Yup, they're related.
For high gravity worts (say >1.080) a 2nd oxygenation/aeration is recommended 12-18 hours* after the first oxygenation (and pitch). Best to apply before there's been any attenuation.

* The timing varies depending on the application.


You surely want to prevent that, or you'd end up with a batch of sweet beer. You could try blending that with dryer beer.
Resurrecting stalled fermentations is difficult, moreso the higher the ABV is.


That should work fine.

Also - thank you for your help.

 

[IslandLizard]

I have 2/3 of the same yeast from a batch 6 weeks ago (not refrigerated but been around 5-10c)

Given that aeration would be seriously difficult if not impossible with the equipment I have, would I be better off to just pitch that in?

As long as it's been handled in a sanitary way, not infected or otherwise tainted, yup, I'd add that it to the batch. But it may contain a fairly large percentage of dead cells after 6 weeks.

Or indeed pitch a new dry pack of nova just to be safe?

Depends on the size of the pack...
If it's a 500 gram pack you definitely don't need to pitch all of that, that would be a tremendous overpitch/waste.

Dry yeast, when pitched fresh, has much of her needed sterol/glycerol/glycogen reserves stored, and generally don't need oxygen upon pitching.
But dry yeast, when reused, is just like any other liquid (wet) yeast, and devoid of those essentials, and needs oxygen to rebuild them.

Meanwhile, you need to come up with a yeast pitch and aeration/oxygenation strategy for your future batches. Especially when you repitch yeast.
You could simply aerate (oxygenate) as you do now using a spray head, or by pumping air through a submerged stainless aeration stone or using a welder's size O2 tank, with a (low-flow) regulator.

There should have been a reasonable amount of O2 in the ro water as it was run open to a pot before pumping in

Once the water/wort is boiled all oxygen has been driven off.

 

[Whisky River]

I agree with the above comments. I think an appropriate pitch of dry yeast would be at least 3-4 of the 11g packets, which wouldn’t need any oxygenation of the wort. That’s what I would do.

I know it’s tempting to try and save money on yeast but I would not trust the viability of 6 week old yeast. Plus if the old slurry hasn’t been kept sanitary, it could ruin the whole batch. For me, using new dry yeast would be cheap insurance to try and save the batch.

 

[OzzyPeeps]

I pitched an 11g pack of dry nova and it was cracking off within about an hour maybe less, leading me to believe it was more or less a false alarm and would have probably been ok ...

 

[OzzyPeeps]

Once the water/wort is boiled all oxygen has been driven off.

I know, but I'm 80 % extract

I do one standard AG batch with 4x hops and "top up" with DME and 15 gal/60l RO. No need for a chiller when my ambient is <= 10c

 

[OzzyPeeps]

Meanwhile, you need to come up with a yeast pitch and aeration/oxygenation strategy for your future batches. Especially when you repitch yeast.
You could simply aerate (oxygenate) as you do now using a spray head, or by pumping air through a submerged stainless aeration stone or using a welder's size O2 tank, with a (low-flow) regulator.

The only thing that has changed in the process in 5 years with no probs is the closed transfer.

Basically the size of the tank is the issue. With a standard batch you can closed transfer without the O2 deadzone being an issue as it will re mix pretty naturally as you ghetto repitch ...

I'm basically making a 20 gal co2 tank now so the sparge head oxygenation won't work.

02 tank is out of the question unfortunately.

I have a couple off ss stones but I don't like running them without microbial filters which are hard to get and only work at aquarium pump pressures which is pissing into the wind at my scale

The way I see it I got 2 options

1) only do a semi closed transfer: I.e. kegs are fully purged but just vent their co2 to atmosphere instead of returning it to FV

This means the surface/meniscus of the beer in the FV is picking up some O2 during transfer as the headspace mixes back with air, but this would only "contaminate" the last keg of 4 if that makes sense, and I'd just crush that one first.

Or ... Option 2: I got myself a cheap 20 quid cordless compressor for airbeds and **** ...

So maybe I fully close transfer, then blow air through the FV to bring O2 back to 21% and transfer with the splash head as normal.

I don't do crazy NEIPAS and ****, just trying to perfect classic lagers and I get through the beer as soon as it's ready

Classic case of " fix one problem cause another one"

I think the best idea is option 1 for my standard flow rate of consumption (leave no beer un-crushed) and when it comes time to go on the dry for a bit use option 2 for longer term storage