A few questions on oxygenation of beer

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Nov 17, 2023
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Hello, I'm currently brewing a saison using wyeast 3724, and as many of you know its a very finicky strain of yeast. I've been using heat wraps to keep the temp at around 93 F but its been very hard to gauge just how close we are to it being done, because there has been a layer of krausen sitting at the top and it doesn't seem to want to fall. FYI its been fermenting for just under 3 weeks now and the krausen is still present. Because of this I've been periodically opening up the fermenter for about a minute at a time checking to see if any of the krausen has fallen (in the hopes that it has and we can take a gravity reading). I've checked on it maybe 6 times so far with no signs of it falling.

My concern now is that I might've potentially oxygenated the beer at this point from constantly opening the fermenter. Should I be concerned? I've now committed to not checking on it for at least another week as I now realize the whole fermentation process is going to take a lot longer than I expected.

Another question I have is in order to get the thermometer inside the fermenter I drilled a small hole on the top where I can pass it through. The hole is covered by a foam stopper similar to this one here: https://www.northernbrewer.com/products/foam-stopper-46-50mm but now I'm concerned that this isn't doing enough at preventing oxygen from coming into the fermenter. What do you guys think?

Finally just out of curiosity I've done a little research on open fermentation as it is quite commonly used for saisons, my question is how do you prevent oxygenation when open fermenting? Wouldn't it be full of oxygen as the fermentation slows down and there isn't enough CO2 to push the oxygen out?

Any help/clarification would be greatly appreciated
Quit opening the FV. There isn't any need to. What you need to do is find some other distraction to keep your mind off of what may or may not be happening inside the FV.

If the beer is still fermenting, letting O2 in shouldn't be a issues. As for temps, you really can get good enough temperature readings from just taping a temperature probe on the outside of the FV below the liquid level with a foam pad or some other insulation over it so the beer temp will not be overridden by the ambient air temperature.

However what's done is done. And it seems you have sealed the hole well enough. Did I mention stop opening the FV?

I think the big thing for those that still do open fermentations is that they have a yeast and beer recipe that makes a lot of foam on the top. And when that foam starts to go away as fermentation is over, they move their beer into a bright tank to store until the off flavors/aromas are taken care of and the yeast and other stuff falls out of suspension.

Most yeast ferment beer in just a few days. So your beer may be done fermenting. But you'll only know that by taking a sample to get a hydrometer reading.

You say it's been three weeks. There's a good chance it's done. Can you get a sample without having to open the lid? If you have a clear FV and can see the beer, then if it's clean enough for you to see clear across the trub layer on the bottom, then it's very likely at FG and reached that quite a few days if not weeks before.

Oh yeah, quit opening the FV. :bigmug: