Originally Posted by AiredAle

If the plastic is HDPE like I think, you will have a problem with oxygen permeating through the walls. I would get the beer out of there as soon as primary is over so you don't get any oxidation. Active fermentation will probably scrub out any oxygen that gets through, but once it's over, you risk staling of your new beer,

Originally Posted by Patton191

I'm assuming ( I'm normally wrong) that you are doing this because you have the fear of oxidation? I am by now means experienced in brewing, but it seems that the whole oxygen permeability idea with plastic isn't very plausible.

Now this is just me thinking out loud here, but it seems that if you have liquid in a container and there is oxygen in the room it still won't be able to get in. It seems to me that the air would be equalized and unless somehow the aquatainer started sucking in air I don't think oxygen would necessarily flow through the brew.

Basically what I am saying is in my mind the oxygen permeability fear is hogwash. It is like when a car gets submersed in water, the pressure inside the car is less than outside in the water, so water will attempt to rush in in order to equalize it.

For the record I left my Red ale in the aqua tainer for 3 weeks and around 4 days and I tasted one after a week in conditioning and I couldn't notice any hints of cardboard or off flavor, but if you wanted to secondary after 10 days that would be fine too.

Originally Posted by SumnerH

You'd think, but that's not how it works. If you have a permeable container that's pressurized with CO2, oxygen will continue to enter until the concentration of O2 inside matches that outside (even though the total pressure inside is much higher than outside).

It's called "Dalton's law" or "the law of partial pressures" if you want to google for more info. 1st semester college physics covers it.

That said, I think the oxygenation concerns are overblown simply because the level of permeability is tiny (and probably dwarfed by the exchange even at a well-sealed neck).

Originally Posted by SumnerH

You'd think, but that's not how it works. If you have a permeable container that's pressurized with CO2, oxygen will continue to enter until the concentration of O2 inside matches that outside (even though the total pressure inside is much higher than outside).

It's called "Dalton's law" or "the law of partial pressures" if you want to google for more info. 1st semester college physics covers it.

That said, I think the oxygenation concerns are overblown simply because the level of permeability is tiny (and probably dwarfed by the exchange even at a well-sealed neck).