[Carson B]

I've looked all around and can't seem to find a real answer to this question, and perhaps there just isn't a good answer. Happy to read an existing thread if this has been answered.

Anyways - I brew my higher gravity beers (OG>1.085) in 2.5 gallon batches. I use a diffusion stone with pure oxygen to aerate and have recently purchased a flow meter for my next batch. It struck me today after a few batches using just the twist regulator that I really have no idea how much oxygen is diffusing into the wort.

I've read multiple times that to achieve around 10 ppm in a standard 5 gallon batch, you'd need pure O2 at 1L/min flow rate for 60 seconds. Should I halve this time for a 2.5 gallon batch...or is there really any risk of over-oxygenating that high gravity of a wort if I go the full 60 seconds? I figure I'd probably want over 10 ppm for a beer this big anyways.

Thanks in advance!

[Robert]

I think that 1L/min is probably excessive in most cases.  You want to find a flow rate where bubbles just barely reach the surface, and you don't have a lot of them breaking the surface making foam.  (For me, in a ~6 gallon batch, that's under 0.2L/min, but it will differ for you.) Oxygen that's breaking through the surface isn't getting dissolved, obviously; you want your O2 dissolving before it has a chance to escape.  Then the question is how long to run it.  You could buy a Dissolved O2 meter for big $$ and oxygenate until you hit a certain arbitrary level.   Or more practically, you could just do this empirically.  Give your wort an arbitrary minute or two of oxygen, and only adjust your procedure if fermentation performance seems to warrant it.

[Carson B]

Thanks for the advice, Rob. I might just be overthinking this one a little. I considered a DO meter until i looked at those prices! I think I'll just stick to the minute or two and assume that's good enough for a newish home brewer haha

[denny]

Pitching large amounts of healthy yeast reduces or eliminates the need for aeration

[Visor]

Oxygen absorption isn't only dependent on flow rate and time, the pore size of the stone plays just as great of a part, O2 from a 0.5 micron stone will dissolve into solution much faster than from a 2 micron stone.

[Carson B]

Also good advice. I'd taken that into consideration, as most of those aeration studies use the 0.5 micron stone for testing.

[Robert]

I used a 0.5 micron for a long time.  I switched to a 2 micron and am happy with it for this reason.  Yes, you need to dial back the flow rate and extend the time to get the same O2 level, but that's simple enough.  On the other hand, getting fluids into and through a 0.5, and getting residue out, is very difficult, so cleaning and sanitizing a 2 micron is much, much easier.  Trade off.

[Kevin]

Pitching large amounts of healthy yeast reduces or eliminates the need for aeration

I'm in this camp. I stopped aeration some time ago and focus mainly on having healthy, active yeast that are ready to go to war.

[denny]

Pitching large amounts of healthy yeast reduces or eliminates the need for aeration

I'm in this camp. I stopped aeration some time ago and focus mainly on having healthy, active yeast that are ready to go to war.

It's been so long since I've aerated I honestly can't remember when I did it last.

[ynotbrusum]

I aerated an English Bitter last week with a wine de-gasser to give it a good start with OYL-011.  It was 1.040 OG and fermented at 57-59F (cold for Brit yeast, I know - I was looking to suppress the esters a bit, but wanted to still help the yeast out with the O2).  Fermentation completed in 5 days.  Can’t wait to taste it.  But I don’t heavily aerate anymore on most beers.  The fear of contamination of the stone drove me away from O2 by canister...boiling was a PITA and Iodophor seemed inadequate with the porous nature of it.

[Robert]

The fear of contamination of the stone drove me away from O2 by canister...boiling was a PITA and Iodophor seemed inadequate with the porous nature of it.

I've never boiled a stone.  Seems to me it will just cook any residue on harder.  A 2 micron stone is easy to soak/flush with iodophor, which is also useful as a cleaner for stainless (just like its halogen cousin bleach, dissolves organic material.)  I also have a sterile filter in line between the regulator and the stone.

[ynotbrusum]

I had a double batch dayonce with a soaking in Iodophor between batches.  The second batch got infected, which I blamed on the stone...but maybe it was the Iodophor sitting in the sun or another cause...I think you may be right:  I also used a sterile filter inline ahead of the stone, so it probably didn’t come by way of the stone.

[Bilsch]

It's been so long since I've aerated I honestly can't remember when I did it last.

If you brew a lot of lagers at or below 50f you will know if you forgot to oxygenate properly. Even if you pitch at 2.5 without the O2, the lag is unbearably long. With the aeration I consistently see active fermentation in under 5 hours @46f, with a little zinc in there as well, closer to three.

[Carson B]

Interesting to hear people do not aerate. I'm fairly new to this, but apart from sanitation and healthy yeast, aeration is about the biggest "most important" tip I've heard repeated over and over again.

I normally would not be super worried about the details on this, but I'm about to brew the biggest beer I've ever attempted, which will include a second aeration 12 hours post-pitch, and I want to make sure I get it right. I've had some disappointing attenuations (around 60-65) on bigger beers recently and am seeking to figure out exactly what the issue is.

[hopfenundmalz]

I don't aerate for British ales under 1.050. for bigger ales I do. Lagers always get O2.

It depends on the beer I'm making, and the yeast I'm using.