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We brewed a maibock (from an extract kit) and when we checked our OG it was significantly lower than it should have been. I mean like, really, really low. We decided to attribute this to the wort not being mixed in good enough so we shook it up and took another reading. Still low. We decided to pitch the yeast anyway and then put it in the fridge. Well, after a month or two it's definitely not good beer based on the hoppy flavors and lack of activity. We added some nutrient and the yeasts woke up for a little bit but died off again shortly after. The evidence points to that we didn't get enough sugars in there somehow. We followed the instructions but something must have went wrong. I can get some more details later.

Is there anything we can do to salvage the batch? Why was our gravity so low?

Edit:

Maibock Extract Kit w/ Specialty Grains purchased from the Milwaukee location (we haven't had issues with any of their other kits)

The original gravity measured about a 1.035 after mixing it several times. It did seem a little watery (not fully dissolved) but I'm not sure why this would have been. Since pitching the gravity did lower a little bit but stopped decreasing early on.

The temp has been around 42-44F since the start.

After checking the gravity several weeks later, it is still at 1.030 and hasn't really moved in a couple weeks.

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Do you have recipe details you can post? Was it all grain or extract? –  Northern Brewer Chris Apr 21 '11 at 16:17
    
If you're asking about why your low gravity was so low, can you basically post the expected gravity and what you measured? –  jsled Apr 21 '11 at 16:50
    
@jsled I will have to get back to you on the details. They're written on the instruction sheet at home –  Joe Philllips Apr 21 '11 at 17:17
    
The wort should be basically watery. At what temperature did you take your gravity reading? 42-44F is way too low for a proper primary fermentation, even of a lager. I have too many questions, and there's too many red flags, here; you should really describe exactly what you did in detail to get a good response, here. –  jsled Apr 22 '11 at 3:27

2 Answers 2

In you comment to Northern Brewer Chris, you mention refractometer...

If your refractometer was wet that can dilute your sample significantly. Also you should check the refractometer for calibration. Does it read zero brix with water? Its very easy for some models to become out of calibration. Furthermore, you need to make sure you deal with temperature.

Lastly, and I don't mean to be an ass, with the refractometer you need to multiply by ~4 to convert brix/plato to gravity.

EDIT 4/22/11
You have done something really wrong if it went from 1035 to 1030.. I think you should get a new hydrometer or borrow one and check the gravity. There is no reason for your gravity to be off with an extract kit. I fear its your measuring equipment still.

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We dried it off and tried it several times. We have had it calibrated using distilled water and it reads zero. I don't know the formula for adjusting for temperature but I'm willing to bet it doesn't make that big of a difference. Our gravity wasn't even remotely close to what it should have been. –  Joe Philllips Apr 21 '11 at 19:25

The most likely scenarios for lower than expected original gravity are volume and sugars left in the kettle. If you had grater than 5 gallons in your fermenter you have in effect watered the beer down decreasing the sugar concentration. Also whatever liquid that was left in the boil kettle or was absorbed by the hops contained sugar and if you added water to reach your target volume this will decrease the overall sugar in the wort.

Stratification of the wort can also give you a lower OG reading since the heavy sugars tend to be at the bottom, especially when you top off with water. You did say that you shook the carboy but you may not have gotten it fully mixed.

To minimize these factors and to hit your target OG you can use a hop screen to filter out the hops and to collect as much wort as possible from the boil or use a nylon hop bag while boiling. You should also mark the 5 gallon mark on you carboys to ensure that you are not exceeding the total volume. If your system is consistently short due to these factors you can always use some DME to increase the sugar content before you pitch your yeast.

As far as salvaging the batch there is not much you can do at this point. You can try brewing another batch with a higher OG and less bitterness and blending the two. I wouldn't recommend doing this though because you may end up with two batches that are not very drinkable and the blending results may vary.

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I do not think the volume of water had an effect. We tested it with a refractometer before adding any water and it was still really low. We also filtered out the hop pellets/chunks while pouring into the carboy using a screen. I haven't tried DME before but I will try to have some around in case this happens again –  Joe Philllips Apr 21 '11 at 17:16
    
Have you calibrated your refractometer lately? If you added the 9.15 pounds of LME and steeped the specialty grains your OG should have been 1.068 in 5 gallons. What OG did you measure? –  Northern Brewer Chris Apr 21 '11 at 17:24
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Shaking almost never mixes the wort well enough to get an accurate reading. If you brewed from a kit, used all the ingredients that were provided, and made the volume specified in the kit, you got the correct OG no matter what your reading was. –  Denny Conn Apr 21 '11 at 17:49
    
I experienced this today - the problem was that I took a reading before shaking the fermenter for about 3 minutes. Taking a reading after this mixing gave me the figure I expected (1.050 vs 1.032 before) –  daveb Jul 14 '12 at 17:11

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