Beer Forum

In order to reach an optimal fermentation temperature for certain styles i cool the wort down on brew day with my copper coil chiller and once i reach ground temps it's difficult to go lower. So, i let it drop in my chest freezer over night and pitch in the morning.

I also oxygenate the night before b/c my oxygen tank is large and on a cart with an acetylene tank in the garage where i brew & my chest freezer is inside my house. It's easier for me, don't have to transport full carboy 2x.

Is it okay to let the oxygenated wort sit over night? Will the 02 still be present (enough) for the yeast the following day. Usually the wort sits for 10-15 hours...

A limited amount of oxygen will dissolve into solution and I wouldn't rely on how much gas will stay in solution for that whole time. Although it does help that you are cooling the liquid, you would be better off hitting the wort with oxygen again before pitching.

Actually, I'm not sure about this one, but oxygenating that long before pitching yeast may just be giving spoiling bugs a jump start...

I wouldn't do it. It would be more prudent to lay some CO2 on the wort to protect it overnight. I had good results oxygenating 40 sec/6 gl fermenter just prior to pitching. If you can see the ferment thru glass or clear plastic using a good starter I would describe the activity as violent within 12 hrs.

I have used this method in the past and it seems to work ok with an appropriate starter. I usually hit my FG or am in the neighborhood. But, I was not sure if it would have a negative effect. The co2 blanket is a good idea.

Ill post back with a fermentation update, the IPA is in a glass carboy so i'll be able to see whats going on.

You'll end up getting more O2 into solution if you are adding it to a cooler liquid. Some of the oxygen is likely still there in the morning, but it's possible the much of it has left the solution or possibly reacted with other components in the beer. Best bet would probably be to do it day of, but understand your cooling/transport issues. Another possibility is to chain a pre-chiller into your immersion set up. Basically running two chillers in series, with the second one in your pot. Get it down to ground water temp, then the first chiller goes into a ice bath. Your cooling water will be significantly lower than groundwater temp as it passes through your immersed chiller. It's a solution, but requires another chiller and using a bunch of ice each batch.

I suppose you could still use just one chiller and detach it from the faucet and use a funnel to pour ice water through the chiller..

Water at room temperature in equilibrium with the atmosphere will contain about 8.5 mg/L DO. Presumably you oxygenate in order to get more than that into solution. If you bubble O2 through room temperature water the DO can be raised well above saturation but as soon as you turn the O2 off the DO level tries to get back to equilibrium. So if you want the solution to stay above saturation you must keep the headspace from equilibrating with the atmosphere. I guess you could do this by corking the carboy. If you run enough O2 through the wort/carboy that essentially all the air is displaced by O2 and then seal the mouth well enough the amount of DO in the wort will actually increase over night as the temperature drops and O2 becomes more soluble. Caveat: movement of O2 from the headspace to the wort, contraction of the wort and contraction of the heaspace gas will all contribute to a drop in headpace pressure so be sure any stopper is fat enough that it doesn't get sucked in.