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Best way to accomplish low oxygen transfer with ported BMB?

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DVCNick

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I did some fermentations in a glass carboy, but didn't take long to switch to the ported plastic BMB: 1) lighter 2) no chance of catastrophic breakage/injuries. 3) I love the port/spigot drain.

Anyhow, I can't find an example right off of someone doing a low oxygen transfer with one, and I think that one disadvantage it might have vs. the carboy is that the top will be less able to contain pressure (any pressure at all) but I think I'm about to find out.

My normal transfer setup is to put the BMB up on the counter, pull the airlock, and gravity drain through the spigot, through the removed lid on the keg. So far I've made no attempt to flush air from the keg, so despite my best efforts there is some turbulence in the keg, until the end of the hose is submerged about an inch. I'm sure there is opportunity for some oxygen uptake here. Also, the fermenter is drawing in air from above that will be gradually mixing with the existing C02. No turbulence though.

So of course I want to purge the keg, probably a full liquid purge. I'm trying to figure out the best plan on exactly what I can do with the equipment I have. Questions:

1) On the actual drain into the keg: I see a lot of people use pressure to push liquid in through the liquid port. Is gravity alone enough pressure for this? Keep in mind most of my beers are dry hopped and currently not cold crashed, so some hop debris will be present. Not much, and I don't normally consider it a problem, but with that tiny little post opening with very low pressure, I'm wondering.

2) If a transfer through the liquid port is unlikely to work in this scenario, is it worth it to bother purging the keg if I'm going to have to take the lid off anyway? I could purge the keg, then take the lid off and transfer quickly, just make sure the surrounding air is as still as possible to prevent mixing (ceiling fan off, no breathing in it etc). Draining into the bottom, hopefully that would still give some benefits in terms of less opportunity for oxygen uptake?

3) How bad is it to let air into the top of the fermenter during the transfer? Ideally I would like to figure out a way to hook up the gas to the top of the fermeter and just barely crack it open, maybe to 2 PSI or something, but I haven't looked to see if I can actually do that with the gear I have, and I'm not sure if the BMB lid would be gas-tight even at 2 PSI. If I had some seepage just during the transfer time, it probably wouldn't waste all that much gas though.

Thoughts on the best thing to do with my current equipment?
 

Jag75

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My buddy has a BMB . We attach a hose from spigot to keg outpost. A hose from the gas post of a keg into the airlock hole of the fermenter . Just make sure the keg doesnt have too much pressure or it will pop off the top , as I found out the hard way. Or we just hook up a co2 tank to the top of fermenter with 2 psi . These both work like a charm .
 

Bassman2003

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It depends upon how "low oxygen" you are trying to be. A true low oxygen transfer would be before the yeast are finished followed by spunding in the keg to scavenge the remaining oxygen. Tranferring the still beer will result in some O2 no matter what.

You could try the CO2 ballon method that Brulosophy does. They capture the CO2 from fermentation in a balloon and then use it to go back into the fermenter during transfers. But you need a large space in your fermentation chamber.
 

Amadeo38

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I recently purchased the ported BMB as well and tried what jag75 describes above. It was a NEIPA and it didn’t work that great, but I think it’s because my port got clogged with hops. It ended up being worse (O2-wise) than a regular transfer because it took over 20 minutes to drain even pushing 2PSI through the top.

And by the way, the BMB does seem to do okay with 2PSI. I hooked up a gas QD to a metal carb-a-cap attached to a piece of silicone tubing that fit over the straight rigid tube part of a 3-piece airlock, then shoved the airlock into the #10 bung in the BMB lid. Worked pretty well, but I did have to hold down on the bung to keep it from popping up.
 
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DVCNick

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Thanks... I guess clogging the liquid port with hops is my main concern. Sounds like it might be an issue.
 

Jag75

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It will clog with hops unless you use a bag. I always bag now because of hop particles clogging . It's a royal PITA.
 

Amadeo38

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It will clog with hops unless you use a bag. I always bag now because of hop particles clogging . It's a royal PITA.
It’s a hard decision for me - get better extraction of oils, aroma, etc. by throwing in loose hop pellets, or have an easier time down the road by using a bag for whirlpool and dry hops.
 
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DVCNick

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Due to the presence of dry hops in this one, I just purged the keg and then removed the lid and tried not to disturb the air as the transfer was happening through the open lid. Also just let ambient air flow in through the top of the fermenter. No idea if that will be better than nothing.

The setup like pictured above will probably work great for my next beer with no dry hops though.. will try that some day. Thanks.
 
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