Added 25g Citra and 20g Galaxy via the Fermzilla’s collection jar, reducing the pressure and partially draining before disconnection, equalising against the vessel before releasing the hops. One or two challenges were overcome along the way, overall a successful operation.
Removing the Collection Jar
The last time I did this I ended up with quite a mess despite completely de-pressurising the Fermzila before removing the jar. I think it was because I de-pressurised after closing the butterfly valve, which left the collection jar under pressure and a small amount of trub below the butterfly valve yet above the lip of the jar. This was released violently as soon as the jar came off.
Depressurising completely also causes trub to swirl around from the bottom and somehow seems disrespectful to the beer after it’s been sitting there patiently at 10 PSI thanks to the spunding valve, so this time I only reduced the pressure to 5 PSI, shutting the butterfly valve afterwards so that the collection jar too was at 5 PSI.
All I had to do now was see if I could get the trub level down past the rim of the jar before unscrewing it – not really necessary, but I wanted to see how cleanly I could do this. I rigged up some silicone hose to a barbed disconnect and a plastic valve that came with a bottling kit which I never used. 5 PSI shouldn’t be enough to dislodge the hose so I didn’t bother with zip-ties.
The device worked really well, pumping out some thick gunk enthusiastically at first, then more slowly as the pressure inside the jar dropped off. I regretted not fitting a second ball-lock to the opposite side of the jar since the flow was bound to stop soon without air getting in to balance things out, but it carried on dribbling happily until I stopped it after 10 minutes and what looked like 400 ml of yeasty gunk.
Removing the collection jar was as difficult as last time despite me greasing the O-ring with silicone lube before assembly, and would have been impossible without the supplied rubber strap wrench. Even so there’s precious few hand-holds to keep the Fermzilla in place while you wrench away, and you have to be sure to place the strap around the very base of the collection jar in order to prevent the thing from flexing dangerously. When it finally came loose I didn’t spill a single drop of crud, and was pleased to see the level in the jar about half an inch below the lip. Result!!
Refitting and Purging
Having dumped the contents of the jar it’s time to strip off the caps and give everything a steaming hot wash before refitting and sanitising. I’ve not used the collection jar lid before and decide to dig it out so that I can shake it vigorously and foam up some sanitiser, which leaks copiously and I discover that the lid has dislodged the O-ring. Great. Now I have to wonder if it’s been damaged and / or if the same thing will happen when I fit the jar to the Fermzilla. Nothing for it but to add my hops and carefully screw it on while checking with a torch. Thankfully the jar is transparent and I think it looks OK.
I hook up my CO2 to the carbonation cap and dial in 5 PSI, flicking the coke cap repeatedly to flush the jar. I’m not really satisfied with this arrangement; each purge only mixes the oxygen in the jar with CO2, diluting it a little more, but never fully eliminating it. Each purge also takes with it a chunk of hop aroma, which smells very nice but I’d rather it stayed in the beer. Difficult to know where to draw the line, so I go for half a dozen quick purges and resolve to pop the pressure relief valve a couple of times when the hops are mixed in. By then any oxygen will also have gone through the beer, but it’s better than nothing.
#idea: going forward I want to knock up a silicone tube elbow to a second carbonation cap fitted to the collection jar. The silicone elbow should go to the very top of the void, touching the middle of the butterfly valve. I’ll add CO2 via the opposite carbonation cap, slowly purging it via the tubed cap. Hopefully purging slowly will minimise the mixing of oxygen and carbon dioxide, and drawing from the top of the void should give me oxygen first and CO2 later.
Equalising the pressure in the collection jar and the Fermzilla was a good idea. When I slowly opened the butterfly valve I didn’t get the same explosive upward surge as last time, just a gentle mixing of gas, beer, and hops. Move gas disconnect to the top, dial in 10 PSI, pop the PRV a couple of times. There’s no leaks and the hops are well and truly mixed in, as is some of the previously settled matter because the beer is more cloudy and lighter in colour, a bit like it was in the last few days before clearing. Final step is to remove the gas disconnect and fit the spunding valve, cranking it right up. Although I’m sure fermentation was done before I dry-hopped the agitation of yeast and addition of new material could result in some activity, and I want any subsequent CO2 produced to help with carbonation instead of escaping to the atmosphere, taking my precious hop aroma with it.