Better Aeration = Better Attenuation

Discussion in 'General Brewing Discussions' started by J A, May 11, 2017.

  1. J A

    J A Well-Known Member

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    The last Pale Ale I did got much better attenuation that I've been getting - 1.056 to 1.007, 87%, for a very crisp, clean beer.

    I think a couple of things contributed. I mashed fairly low so that helped, but I do that a lot and seldom get much better than around 80-82%. I did pitch slightly more yeast because I had a split batch with two 3.5 gallon beers and used a whole packet in each. I'm sure that didn't hurt but I've pitched slightly over or under before and don't count on a big difference.

    The thing that was definitely different about this batch is that I really aerated the crap out of it. I used a wire whisk in a drill for 3 minutes and there was about 2 inches of foam on the top when I got done. I pitched the dry yeast right on top of the foam and it really went to work.

    I pitched and fermented at 65 or so. I peeked into the buckets on the next day to be sure things were going and there was very nice krausen. I didn't check gravity until day 6 and it had gone to 1.011. I didn't expect it to go much beyond that so I took the buckets out of the temp-controlled chamber and put them in a corner of the dining room where they'd stay around 70.

    I checked gravity again on day 9 and it had gone to 1.007 and was clearing. I can't say for sure it wouldn't gone lower, but I didn't want it to be too thin and dry and went ahead and put the buckets in the fridge for crashing and kegging.
    Just kegged the beer the other day and sampling last night, it was pretty great. It may be one of the best beers I've produced. Simple malt bill, big hops, clean fermentation, great attenuation. It all worked!

    I'll be working on my aeration regimen for the next few batches, but I bought a pump and diffuser stone and figure on letting it run a while on every batch from now on!
     
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  2. Ozarks Mountain Brew

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    yup, I always emphasize lots of oxygen, people just don't get how much you really need, I have 3 " of foam in my buckets every brew session, all the way to the top on my 13 gallon drum fermenter
     
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  3. J A

    J A Well-Known Member

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    Yeah, I've been fighting to get better attenuation and I'm finally starting to get it right. Rocking the carboy, even a whole lot, can only go so far. I'll be very interested to see how things go for next few brews.
     
  4. jeffpn

    jeffpn Well-Known Member

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    I use a stirrer attached to my drill when I'm chilling. If it's spins fast, I'll get lots of foam on top, too much to read my hydrometer. Gotta be air getting in there.
     
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  5. Trialben

    Trialben Well-Known Member

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    Thanks for your detailed thread JA i got some crazy attenuation out of my last batch dropped to 1.006 and it lagged for 36 hours! But first brew i put sugar in for a while thats probably the reasom.
     
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  6. Mark D Pirate

    Mark D Pirate Well-Known Member

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    I've been getting pretty decent results just with shaking the half filled FV ( screw on lid ) and shaking the half full cube as well .

    Not pure O2 yet but its on the cards
     
  7. Trialben

    Trialben Well-Known Member

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    Thats the big question is pure O2 even necessary if fermentomion seems fine without it. Pluss the few brulosophy insignificant results on this.
     
  8. Ozarks Mountain Brew

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    theres a trick to it, I see people all the time add oxygen just to let it bubble to the surface and end up loosing it, the container needs to be somewhat sealed to work properly, the oxygen channels and doesn't absorb correctly

    I have an oxygen wand but I don't use it any more its to expensive
     
  9. J A

    J A Well-Known Member

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    Good thing about an aquarium pump is that it's cheap to use...just let it run as long as you care to. Down side, of course is that it needs proper filtration to keep the uninvited guests out of the wort.
     
  10. Mark D Pirate

    Mark D Pirate Well-Known Member

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    I bought an air pump and that's why I don't use it , had thought about using a scuba tank .
    Easy and cheap to get filled too
     
  11. Nosybear

    Nosybear Well-Known Member

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    Run it slowly. Most advice I see is a minute at bubbling the hell out of the wort. I oxygenate, pure O2, and never use a flow rate of over 1/16 LPM. I figured out how much oxygen I needed to add in grams, converted that to a flow rate and time and basically determinedI can get 1 mg/l (ppm) of O2 into the wort in 1 minute at 1/32 LPM. Not many bubbles reaching the top at that flow rate! It takes 8-10 minutes to get the required amount of oxygen into a six gallon batch doing that but you're not wasting it by bubbling it out the carboy neck!

    For the chemically inclined: At STP (0 degrees C, 1 atmosphere of pressure), a mole of gas is 22.4 liters. A mole of oxygen (O2) weighs approximately 32 grams. I'm at 6,000' elevation so my "mole" of gas is 26.4 liters - pressure here is about 85% of sea level - equaling 32 grams of oxygen at 0 degrees C. We have to use Kelvin temperature to correct to room temperature so the difference is 1-20/273 times my pressure corrected mole of gas for a total volume of a mole of O2 equal to 28.5 liters. Now to the amount of O2 we need: My standard batch is 21 liters. I need 10 mg/liter, or 210 mg of oxygen, 0.210g. Dividing 0.21 by 32, I need 0.007 moles of oxygen. Mutliplying that by 28.5 liters, I need 0.187 liters of pure O2 to aerate my beer. At 1/32 LPM, I multiply 0.187 by 32 to get 5.985 minutes, or six minutes, assuming 100% absorption of the gas by the wort and 100% pure O2, neither of which are true. So, applying a "fudge factor", I get one minute per ppm at a flow rate of 1/32 lpm of welding-grade oxygen.

    So next time your kids say high school chemistry is a waste of time, tell them they'll need it to brew beer! It'll be a little different if your pressure or temperature are different but it shouldn't make that big a difference. 1 minute per ppm at 1/32 liters per minute.
     
  12. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    I think dry yeast requires less O2 than liquid yeast (some dry yeast companies claim it works well without any aeration), but adding O2 is always a good idea.

    Liquid yeast, on the other hand, requires aeration to 8 to 12 ppm for ales and up to 15-20 ppm for lagers. Wyeast did a study and found DO levels with ambient air could only achieve @ 8ppm max. A minute of pure O2 with a diffusion stone achieved @ 12ppm of DO.

    When I started using pure O2 and a stone, my beers took a huge leap in overall quality. In my opinion, it is a must with liquid yeast. Dry yeast is far more forgiving.
     
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  13. J A

    J A Well-Known Member

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    I'm headed toward using O2 but it'll be awhile before I can swing it. For now the fish pump and dry yeast or bigger starters will have to do.
    ;)
     
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  14. MrBIP

    MrBIP Active Member

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    Well now I just feel silly for sticking the wand in the carboy and cranking the hell of it for 30 seconds! :)
     
  15. Nosybear

    Nosybear Well-Known Member

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    All that stuff requires oxygen, a regulator where you can set the flow rate and an airstone. The airstone makes fine, tiny bubbles increasing the surface area of the oxygen in contact with the wort so the wort takes up more of the gas. Just cranking it pours most of the oxygen out the bung. Even if you're just pumping air through an airstone, the smaller bubbles will increase the amount of oxygen in the wort, to a point. It makes a handy equation: One minute of O2 yields 1 ppm in 5.5 gallons of wort yields 1 ppm of dissolved oxygen. I'm going to get a dissolved oxygen test kit and start testing my brews to validate my model, more to come.
     
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  16. LlewellynBrewHaus

    LlewellynBrewHaus Active Member

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    I like my pure O2 set up as well.
    Made a SS wand and attached a stone then a regulator that attaches to the disposable O2 welding tanks. I don't have the fancy one that shows flow rate but, using a mason jar filled with water ,i just crack mine open till bubbles form around the stone but don't make it to the surface. I feel like I'm set pretty close and move over to fermentor and stir around for 1.5-2 mins. I like your thinking @Nosybear look forward to the results !!
     
  17. Brewer #197073

    Brewer #197073 New Member

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    At what pressure would you have to have for the O2? Would an aquarium pump do the job? If so and if it is not a regulate-able pump what would the output have to be to achieve your formula? Does airstone size - 2 or 5 micron - make a difference? I'm hoping an aquarium pump primarily because 1) I am a noobie and 2) I don't have a bunch of extra $$$. Do you have any recommendations for a viable set up? TIA.
     
  18. Aub

    Aub Active Member

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    I have a 2 micron airstone connected to a wand with a hepa air filter on the pump.
    My pump is .03 mpa with a 40L/min output. I don't use pure oxygen, just air and it works a treat, all you need is 5 to 10 minutes and it aerates the crap out of the wort.
     
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  19. Brewer #197073

    Brewer #197073 New Member

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    Thank you very much.
     
  20. Nosybear

    Nosybear Well-Known Member

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    You can simply shake the hell out of your carboy... I use a regulator and have no idea what pressure it operates at. Aquarium pumps work. I use a 2 micron stone, I'd run air at 5. The formula is based on 1/32 lpm through a 2 micron stone. Air is only 20% oxygen so it takes at least 5x as long.
     

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