Bad Hydrometer Reading

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dlittle29

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Just did a weizenbock batch, this is my third time brewing this particular recipe, and when i went to take the OG my hydrometer read 1.010 @ 68*F. To me this reads that there is 0% potential alcohol. I am not sure what i did wrong here. I caliberated the hydrometer with water and it seems to be ok. The only thing i can think of is if the mash in temp was too low? I heated the water to 163*F, added everything to the mash (which i know cools it down some) took another reading and it was at 153*F. This is 2 degrees less than what i wanted but around the target area. My mash tun looses 1*F/2 hours. So my idea that the mash temp was too low seems to be shot. Any one have any ideas??
 
Not enough information and it's not clear what you are measuring. The reason I am saying this is that an OG of 1.010 is extremely low. The only way I can see of being any help is if you lay it all out for us. We would need the recipe including the complete grain bill. Also detail your mash procedure (assuming this is not an extract batch). I'm not clear on how you conclude that an OG of 1.010 would result in a 0% alcohol potential. Even a low OG like that would still ferment out and produce some alcohol and not zero. Perhaps there is some confusion on the terminology OG, FG etc. What we (the fourum we) will be looking at mostly is your efficiency and we can only evaluate that if we know the grain bill and pre-boil volume yield. A low OG is typically the result of something wrong with the crush of the grain or the mashing/sparging procedure. Are you batch sparging or fly sparging for instance? With some more detail we can probably spot the problem or at least point out some possible suspects. Without more info, we are dead in the water (wort). It would be impossible to predict the alcohol percentage knowing only the OG. We would need the FG as well. OG will depend on the mash efficiency and the FG on the degree of attenuation. It's unlikely that the mash temps would make much difference in the OG so long as you are somewhere in the 149-158 range or thereabouts. It may, however, have an effect on the attenuation. So, post back with as much information about the recipe and mash procedure as you can come up with and we will take a shot at it. A little about your equipment setup would also be of help.
 
7lbs Munich
7lbs Pilsner
1.25 lbs Vienna.

Mash in temp @ 155 for 1.5 hours - used 4.25gal water
Sparge water temp 165 - since it cools as it goes through the grain bed

I was looking for an OG of 1.076 - which i have gotten around that the two other times i brewed this recipie. It is a weizenbock that should end @ 7.2% ABV.

There is no FG reading at this point because i just brewed this batch yesturday and this beer sits in primary for 2 months, then secondary for 4.... yes this is a very very smooth finishing beer... but i digress. The final gravity reading i usually get is 1.010 or thereabouts.

I use homedepot 10gal gatorade coolers for both my mash tun and my Lauter Tun. I used 5 gallons of sparge water and just let it run until i get 6.25 gallons of wort for the boil. (i boil for an hour and usually lose 1.25 gallons during boil).

Please let me know if this helps or if you need more detail.
 
OK

1. Assuming a five gallon batch size, the 15.25 lbs of grain should yield approximately 550 gravity units based on a theorectical max yield of 36 pppg. (15.25 X 36) Assuming a 70% efficiency you should be able to get the 1.077 OG. (550 x 0.7 / 5).

2. OK. we are on the same page with the OG definition then.

3. I think I have spotted part of the problem It appears that you are leaving too much wort behind in the mash tun.

Initial strike water volume = 4.25 gal
Lost to grain absorption @ 0.12 gal/lb = (1.83 gal)
Sparge water addition = 5 gal
Net yield: 4.25-1.83+5 = 7.42 into kettle

You ran off only 6.25 gallons which is what you needed to reach the 5 gallons after the boil off loss. This means that there was an additional 1.17 gallons left behind. That's where your big loss was.

7.42 x 10 gravity points = 74.2 gravity units
74.2/5 gal = 14.9 points or 1.015 SG

That's still pretty dismal. Now then, your total water added was 9.25 gallons, or 2.43 qts/lb. That ratio would result in a very thin mash. The suggested water/grain ratio is typically between 1 and 2 qts/lb with most using about 1.5 qts/lb.

From the above, my best guess is that you ran the mash too thin and you left behind 1.17 gallons of wort in the MT. These two factors still don't justify such a low efficiency. Something else is at play and it's most likely the grain crush. You are batch sparging, so channeling should not be an issue. That's all I can think of at the moment. I'm not sure what the effect of the overly thin mash would be, but I doubt that it would influence the efficiency to that degree. Could your volume measurements be off some? That can have a major impact on the calcs. Just guessing now.
 
I actually fly sparge, the extra water was in the lauter tun, and i shut off the flow when i got close to the 6.25 gallons. We didn't have any wort settled in the mash tun at the end we drained it all out into the kettle for the boil. The wort didn't look particularly thin. In fact i felt this was the best looking wort i have had yet (i know looks can be decieving). My coworker (who also home brews) suggested that i might have a stuck hydrometer (always reading the same reading no matter what) i have never heard of this happening before, only broken hydrometers. I will test with a new hydrometer but i feel like it will be off since i already pitched the yeast. Any advice? or have you heard of a "stuck hydrometer" before?
 
OK, it the fly sparging changes my diagnosis. I will again make an assumption that you are using a braid or manifold in the MT and not a false bottom. Either of those are more susceptible to channeling and that could be the problem or part of it. Wort left behind after fly sparging should have very little sugar content, so that should not be an issue.
How well did you stir the grain bed and did you stir it near the end prior to beginning the sparge? That can improve the lautering efficiency considerably and it goes a long way to help prevent channeling problems.

There are varying opinions on fly sparging technique, but I've had the best results by not draining the grain bed completely. I maintain an inch or two of sparge water above the top of the grain bed all the way to the end. IME, this helps keep the grain suspended in the mash for more efficient lautering. This method has worked very well for me.

I doubt that it's a problem with your hydrometer, but it could be. They normally don't get "stuck". I've never seen that happen. It's possible that the internal paper scale has slipped, but if it reads zero with plain water it should be OK. I suppose that you could get one that was not manufactured properly and that could result in a non-linear error that might be more difficult to detect. You could make up a sugar solution of 1.040 SG to check it in the range that you will be using it most of the time. That will tell you a lot. Yes, buy or borrow another hydrometer to eliminate that question.

I really think it is a channeling problem and maybe a problem with the crush as well. It's got to be something major to affect the OG that much.
 
It's almost impossible to get a 1.010 OG with a grain bill like that. Even if you fly sparge that with just a single hole in the bottom of the tun, it couldn't channel that badly. I'm going to assume you buy your grain precrushed and my only quess is that they forgot to crush it this time.

Did you pull your sample from the boil kettle AFTER stirring it well? Are you sure the 1.010 sample wasn't from the last runnings from the tun?
 
It's almost impossible to get a 1.010 OG with a grain bill like that. Even if you fly sparge that with just a single hole in the bottom of the tun, it couldn't channel that badly. I'm going to assume you buy your grain precrushed and my only quess is that they forgot to crush it this time.

Did you pull your sample from the boil kettle AFTER stirring it well? Are you sure the 1.010 sample wasn't from the last runnings from the tun?

+1 but it could be a combination of factors such as channeling AND the crush/lack of crush or stratification in the boil kettle. Got to stir that kettle well before taking the sample.
 
+1 to Bobby


Tell us about your crush - do you crush your grains or does the HBS? How did the crush look?

It's NOT too late to get a sample OG - it may not be perfect once fermentation starts, but yeast itself contribute very little to the picture. Only caution is to sanitize like crazy and be very careful drawing your sample.

your OG above was taken after the boil, right? (stratification issues prior to boil)

Something just isn't right in this picture, and either you took a bad reading, or your grain wasn't crushed at all...
 
WOW ******* MOMENT OF THE CENTURY..... i never crushed the malts HA! wow i feel absolutely retarded right now!

Thank you all for your help.... looks like i am going to have to brew again this weekend!
 
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