How much oxygen (and how much O2 is too much)?

[caskconditioned]

I had 3 batches in a row with serious acetaldehyde issues (last 2 batches have turned out great). Nothing in my brewing has changed except my starter technique and how I oxygenate the wort. Long story short, I think I was having an issue with my O2 set-up and was under oxygenating the wort.

I currently use a 2 micron air stone with those red O2 containers from the hardware store. On my last batch (10.5 gallons @ 1.049) I ran the O2 for 2 minutes. I transferred the batch yesterday and it tasted fine. But this got me thinking about my previous acetaldehyde issue.

Should I be oxygenating for longer?

I am also thinking about buying an air stone I can screw into a "T" and running the O2 while I run-off. I gravity feed at run-off so however long it takes to drain 10.5 gallons (my guess is 5-7 minutes). If I do that will I be adding too much oxygen?

TIA

 

[scinerd3000]

personally i dont oxgyenate but the main person i know that does uses it on full blast for maybe 30-45 seconds. Thats it...and when ive brewed with him ive never had issues.

 

[giligson]

Yes you can over oxygenate but I have no idea when you would hit that threshold.

Remember gasseous oxygen is a powerful chemical and can cause significant changes to the chemicals in your wort.

 

[malkore]

I think 20ppm of O2 is where you're doing more harm than good.

but testing O2 levels ain't simple.

I run my pure O2 for 60 seconds in a 5 gallon batch, moving the aeration wand/stone around the bottom to distribute the O2 throughout.