DDH during active fermentation

[ChaosB]

Recipe I'm brewing calls for two dry hops, one for 6 days and one for 3 days. I'd like to do the first one during active fermentation. I believe fermentation is starting to slow down. This is day 4 since pitching some Conan. I started at 63 F and raised it to 68 F last night at the end of day 3. There's still some foam at the top though high krausen has passed. Bubbling is slowing, and a yeast cake is forming at the bottom but the carboy is still very active with yeast zooming up and down. After fermentation and dry hopping, I plan to cold crash and pressure transfer to keg for carbing.

I'm thinking now is the time to add the first dry hop. Do you agree or should I wait.. a day or more? How much longer should I expect / estimate this to take to finish / clean up?

 

[IslandLizard]

For NEIPAs, lately I've been dry hopping toward the end of fermentation, around 80% done. I used to add the first charge earlier, but think it blows off too much aroma. They're still hazy as can be, even after cold crashing.

I'd take a hydrometer sample, or just eyeball it on bubble activity. This may well be the right time.
Flush the headspace with some CO2 after opening and taking a sample or adding dry hops. Oxygen is very bad for hoppier beers.

Cold crash with a balloon or a bag filled with CO2 on the airlock stem.

 

[Jag75]

@IslandLizard - when you DH at the end of fermentation you just pour your hops in loose right ? I could see how with aggressive beginning fermentation would cause the aroma to be carried out more then the later stage of fermentation. Wouldnt using a bag and sinking the hops towards the middle of the fermenter help keep the aroma and flavor mixed in the beer instead of floating on top and gassing off . I understand people mix or swirl the hops periodically but one cant sit 24 -7 to stir . So if you stir a few times a day that still leaves a lot of time hops are sitting on top.

 

[ChaosB]

How do I flush the headspace? I've got a CO2 tank and a pressure transfer kit. Do I just take the racking cane off and blow co2 into the carboy and let whatever come out the other side of the cap or stick an air lock on the exhaust side

 

[Jag75]

I pull out the airlock and spray the hose with starsan . Then I stick the tip of the hose in the airlock port and purge the co2 at about 5 psi for about 15 seconds then press the side of the bung to allow the o2 to be pushed out . I do this a few times.

 

[IslandLizard]

How do I flush the headspace? I've got a CO2 tank and a pressure transfer kit. Do I just take the racking cane off and blow co2 into the carboy and let whatever come out the other side of the cap or stick an air lock on the exhaust side

What @Jag75 said.^
Just be careful with carboys, don't build up too much pressure a few (2-3) psi at the most.

Or remove the bung or cap and just stick the end of the CO2 hose inside the headspace, swirl around a bit, and flush out for half a minute. Set the regulator at 10-15 psi or so. You can't get all air/O2 out that way, since it's a mixture of gasses, with diminishing returns, but every bit helps.

I stream CO2 into the fermenter when adding dry hops, syrups, or when stirring to disperse dry hops, basically working in a counterstream of CO2. I'm willing to bet very little air if any at all can get in that way.

 

[IslandLizard]

@IslandLizard - when you DH at the end of fermentation you just pour your hops in loose right ? I could see how with aggressive beginning fermentation would cause the aroma to be carried out more then the later stage of fermentation. Wouldnt using a bag and sinking the hops towards the middle of the fermenter help keep the aroma and flavor mixed in the beer instead of floating on top and gassing off . I understand people mix or swirl the hops periodically but one cant sit 24 -7 to stir . So if you stir a few times a day that still leaves a lot of time hops are sitting on top.

Yes, dry hops go in loose, against a gentle counterstream of CO2, here.

During fermentation CO2 is generated throughout the beer, and whatever doesn't get dissolved or adsorbed on the way up, escapes into the headspace, where it mixes with other headspace gasses present. That gas mixture exits through the airlock or blow off tube or leaks out some other way. Some volatile aromas will be lost, stripped out, regardless of whether the hops are loose or in a bag.*

Sure the layer of dry hops that floats on top of the krausen or beer won't interact much with the beer to lend their goodness, while gasses passing through will strip out volatile aromas on their way out. Submerged hops and already extracted flavor and aroma compounds are also subject to CO2 stripping, but probably in lesser amounts or dry hopping would be utopia. That's why periodic (gentle) stirring or swirling/rousing helps submerge that floating hop carpet, while resuspending the hops already submerged in the beer, and those lying down on the bottom. Diffusion is typically slow, but agitation can speed it up tremendously. Like the difference between radiation and convection.

*Submerged or floating bags tend to restrict extraction especially when the hop mass is compacted inside. No beer can get to that dense pulp. Periodic 'blooming' of the bags helps to refresh the beer in and around the hops and thus extraction.

I stir (very gently) right after adding the dry hops and don't have a hop carpet floating anymore. I again stir 4-6 hours later and then 2x a day for the duration, 3-5 days. I may only stir once a day after 3 days though, it's diminishing returns after 3 days already.

Here's a very recent and interesting post on the process and mechanics of dry hopping/agitation/extraction:
https://www.homebrewtalk.com/forum/...rash-cooling-for-racking.666563/#post-8603897
The article this is based on sounds right up our alley.

 

[IslandLizard]

Do I just take the racking cane off and blow co2 into the carboy

As long as the bottom end of the cane stays in the headspace that would work. Bubbling CO2 through the beer at that point is probably the worst you can do.

 

[ChaosB]

Not sure I did this right. How much CO2 should this be using? My regulator dropped from 1000 to 800. This was supposed to be a full 5 lb tank and it was a pain the ass to get filled in Korea. If I used that much CO2 just to purge the headspace, how am I supposed to have enough to carb and serve my beer.

 

[ChaosB]

Are these hop pellets going to dissolve or sink before / during the cold crash?

 

[IslandLizard]

Not sure I did this right. How much CO2 should this be using? My regulator dropped from 1000 to 800. This was supposed to be a full 5 lb tank and it was a pain the ass to get filled in Korea. If I used that much CO2 just to purge the headspace, how am I supposed to have enough to carb and serve my beer.

Wow, that is scary! I never really measured, but I purge a lot using a 20# tank. Usage doesn't show as much or quickly.

Now those dials don't tell us all that much beyond a mere indication of liquid CO2 left. The only way to tell how much gas you used is to weigh the tank before and after the procedure. If this was a "full" 5 pound tank, reweigh it and subtract the tare weight (stamped into the neck).

How long did you "purge" for, and at what pressure setting?

Did you pressurize the headspace (purging) or just stream gas (flushing)?

On a side note, in a glass carboy you really shouldn't apply more pressure than a few psi, 2-3 psi max probably, for all security, but don't quote me on that! Flushing is much safer, and probably just as efficient.
When you flush, no pressure is applied to the vessel, gas just streams in, mixes, and streams out.

With CO2 we brewers generally don't use a flow meter, but you can still measure output volume. At a certain pressure setting, fill a plastic bag (calculate or estimate it's volume in liters) and see how long it takes to fill. Volume/time is your flow rate, liters/minute.

1 pound of liquid CO2 (in your tank) has a volume of 243 liters (8.57 cubic feet) when expanded (at atmospheric pressure, 15°C).
It would fill a cube 62.4 cm high.

 

[ChaosB]

I ran the gas hose into the carboy and let it stream at 2 psi while I was dumping my hop pellets in, then I covered it with the cap as much as possible and let it go for another 30 seconds or so.

The regulator came with a flat plastic gasket zip tied to it so I initially put it inside the connection port. This did not offer a tight seal and was leaking so I took the gasket out, I was then able to tighten it more and make a good seal.

 

[IslandLizard]

I ran the gas hose into the carboy and let it stream at 2 psi while I was dumping my hop pellets in, then I covered it with the cap as much as possible and let it go for another 30 seconds or so.

That's the best way IMO, gas comes out, air can't get in. Probably took 2 minutes all together? A slow stream of gas is plenty for that. As I mentioned before, you could measure the volume per minute using a (smallish) plastic bag how much gas that method uses.

The regular came with a flat plastic gasket zip tied to it so I initially put it inside the connection port. This did not offer a tight seal and was leaking so I took the gasket out, I was then able to tighten it more and make a good seal.

Some regulators have a rubber o-ring in the connector tube, they don't need a fiber or plastic washer. A leak at the valve connector can lose a lot of gas in a short time, the pressure there is 1000 psi or more. But they're not sneaky, you can hear it.

Also, open or close the valve all the way. Never operate half way open. The valve has a packing that needs to compress in the top position, and can only do that when it's all the way open.

Also check for leaks in other areas. A slow leak you can't even hear, over a few days can drain your tank.
Use bubble juice or a thick dishwash soap solution and brush it on. Spraying Starsan can also detect leaks, but it doesn't stay put very well.

I recommend weighing to trace usage when it seems excessive.