pressure fermenting 20L batches in 55L fermzilla - any concerns?

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buckerooni

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got a buddy who wants to get into home brewing and has lots of bbqs at his place etc. Really wants to experiment with brewing, so will start with small batches but will want to brew slightly larger quite soon.

Any issues doing 20L pressure fermenting on a 50L fermzilla?

I'm assuming the pressure fermenting mitigates the oxygen issue that may occur with non-pressurised fermenters of similar size.
 
I guess it would depend on how much oxygen the yeast can consume, otherwise you will be pressurizing with an O2&CO2 mix. Perhaps flush it slightly with CO2 first to reduce the amount of oxygen.
 
got a buddy who wants to get into home brewing and has lots of bbqs at his place etc. Really wants to experiment with brewing, so will start with small batches but will want to brew slightly larger quite soon.

Any issues doing 20L pressure fermenting on a 50L fermzilla?

I'm assuming the pressure fermenting mitigates the oxygen issue that may occur with non-pressurised fermenters of similar size.
A 20 litre batch will produce around 2 kg of co2 so doesn't really matter either way, certainly enough co2 produced to purge the oxygen out of the fermenter.
 
Hi,
In general I would not recomment puring oxygen from a fermenter with carbon dioxide. The yeast will consume the oxygen fast enough.
Once fermentation kicks off the fermentation vessel should naturally start slightly pressurising due to the release of carbon dioxide however I would recommend venting the pressure with an airlock as much as possible while preserving a very slight positive pressure.
I have found that some yeast react negatively to increased pressure and flocculate out of solution (potentially before the completion of fermentation).
There should be no problem with adding pressure with sterile carbon dioxide at the end of fermentation to promote yeast flocculation and increase clarification without filtration.

Essentially, if you don't have a leaky fermenter, you should not get oxidation in a fermenter once the yeast has consumed it all and replaced the headspace with a layer of carbon dioxide and there is no need for pressurisation and the homebrew scale.
 
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