# Can you over oxygenate wort?



## Wrayza (8/1/15)

So I'm finding mixed opinions while searching, this might end up being a good little experiment. 

Here's what I've stupidly done. 

Brewing an AG 23L Belgium strong dark, OG 1.079 and adding candi sugar to fermenter later. Would be 1.091 if I had have added it with everything else. 

Wyeast Belgium Ale #1214, over the top 16L starter (1.032 using LDME) which should result in around 500 billion cells, no problem there. Fermented, crashed, drained and 1.079 wort pitched on to cake today. 

Decided to give it 90 seconds of pure o2. Opened my new o2 regulator all the way, I didn't even consider flow rate!

Later I estimated the flow rate I had used with a plastic bag within a 1L disposable water bottle and a stopwatch. 

Easily 6L per minute!

Needless to say I've ordered a flow meter and won't use pure o2 again until it arrives. 

I'll update with any activity and the final result. Maybe worth mentioning the wort was 16-17 degrees when I aerated, I'm hoping o2 is less soluble in lower temperatures.


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## Blind Dog (8/1/15)

O2 is more soluble at lower temperatures not less, unfortunately


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## Wrayza (8/1/15)

Haha, there goes that wishful angle.


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## Blind Dog (8/1/15)

personally, I think you'll be fine. Even at full flow, 90 seconds isn't a great deal of time and the yeast are likely the chew through the oxygen that doesn't come out of solution pretty quickly. From the sources I've read p, over oxygenation may lead to a faster fermentation with the generation of more esters and favouring yeast growth over alcohol production. More esters may be no bad thing


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## Wrayza (8/1/15)

I've recently read the same thing of favouring yeast growth over alcohol production, but not that it can cause more esters. 

You're spot on, it may work in favour of the style. Hopefully that is the only repercussion of too much oxygen. 

Time will tell, first test will be if it hits it's target fg.


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## barls (8/1/15)

the answer is yes, but probably not with what you have done.


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## jlm (8/1/15)

I'd wager your wort hasn't absorbed anywhere near the volume of O2 that went out of the bottle in that time, unless you've got 10 odd diffusers hooked up in parallel. Worst case you've wasted a couple of dollars in gas.


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## GalBrew (8/1/15)

Should be fine. Not ideal, but as others have said most of that won't be absorbed by the wort.


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## Wrayza (9/1/15)

Thanks for the replies guys, so far I've had serious air lock activity within 12 hours and it hasn't even hit high krausen yet. Might be ok!


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## Dips Me Lid (10/1/15)

" Wyeast Belgium Ale #1214, over the top 16L starter (1.032 using LDME)"

A 16L starter? That seems pretty big, any reason for such a large starter wort?


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## Wrayza (10/1/15)

I only have 1L flasks which wouldn't have been large enough to reach the correct pitch rate. 

I had 1.5kg of LDME and a spare fermenter, figured I would keep the gravity around 1.030 and go as large as possible seeing as I wouldn't be stirring or agitating at all. 

Bit of a waste of LDME bit it was lying around from ages ago, full volume boiled of course.


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## Wrayza (24/1/15)

Currently sitting at 1.017, just a tad off the predicted fg of 1.013.

Think I might leave it another couple of weeks and take another reading just in case it's gone sluggish at the end. Still some very very slow activity which could just be left over co2 coming out of solution. 

I've got some oxygen absorbing caps for this batch, expecting it to take some time to mature and also to drink.


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## zappa (24/1/15)

Based on my own observations, I've found that over oxygenation with pure O2 leads to a rigorous early ferment that stalls significantly higher than expected FG (generally about 10% above). Could be because I've under pitched, but I never have the same problem when I don't use pure O2 to oxygenate.

I recently purchased an oxygen flow meter from uxcell, so I'm going to do some further tests in future with recommended flow levels.


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