I know, RDWHAHB, but... - Home Brew Forums

 Home Brew Forums > I know, RDWHAHB, but...

03-23-2010, 02:24 AM   #1
RushN24
Recipes

Jan 2010
New Jersey
Posts: 124
Liked 2 Times on 2 Posts

Ok I did my first partial mash today and everything seemed to go fine until the end; I missed my target gravity by a pretty fair amount.

I mashed 4.75 lbs of grain (3lbsMO, 1lbs Crystal 20, and .75 biscuit) with 5.94 qts of water at 154 for 60 mins, batch sparged and came out with 2.35 gallons at a specific gravity of 1.049. This would give me a pretty fair efficiency of about 65.3% (I can post my calculations if necessary).

So here is what I figure 1.049 in 2.35 gallons gives me 1.023 in 5 gallons. In the recipe I am also using 4lbs of Light DME with a potential extract of about 1.044. So I calculated (4*44)/5 = 35.2 which equals another 1.0352 in five gallons.This puts my target OG at 23+35.2 = 58.2GU or 1.0582 am I right? Check my math but the calculations are fairly straight forward. At this point I feel like I am right on track to hit my target OG becuase I assumed an efficiency of about 67.5% so I am not far off. All that's left now is to boil and add the hops and DME, can't really mess that up too much so thats what I did.

Transferred everything to the carboy and to my dismay my measured OG in 5 gallons was only 1.052 (1.051 corrected for 70*F). How could this have happened when all I did was add DME, I did not have any boil overs, and I ended up with exactly 5 gallons. Any ideas what went wrong, am I just missing something here?

Thanks in advance, this beer is going to be amazing either way, and I am enjoying some Apfelwein to ease my concerns,I'm just truly puzzled
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“Filled with mingled cream and amber I will drain that glass again. Such hilarious visions clamber Through the chambers of my brain -- Quaintest thoughts -- queerest fancies Come to life and fade away; Who cares how time advances? I am drinking ale today.”

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03-23-2010, 02:43 AM   #2
whatisitgoodfor
Recipes

Nov 2009
Austin
Posts: 239
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Did you cool the hydro sample you took for your mash gravity sample, or just do a hot measurement and a temperature adjustment tool?

A small mistake in the temperature of the wort when you read the hydro could make up for the difference. Your math is good according to beersmith.

03-23-2010, 03:14 AM   #3
RichBenn
Recipes

Aug 2009
Tahoe
Posts: 842
Liked 23 Times on 21 Posts

Quote:
 Originally Posted by whatisitgoodfor Did you cool the hydro sample you took for your mash gravity sample, or just do a hot measurement and a temperature adjustment tool? A small mistake in the temperature of the wort when you read the hydro could make up for the difference. Your math is good according to beersmith.
I had this exact same problem. Hydrometer temperature adjustment doesn't seem to work as well when one is 100F or more. I now cool down to below 80, then adjust, and the math all makes sense again...

One other thing to look at is whether the wort was stirred up. Sometimes when one samples in stream, it's way different than when the wort is mixed.

Finally, do a carefull analysis of your volumes. Wort expands at temperature, maybe you were more or less than you thought.

03-23-2010, 12:40 PM   #4
Reelale
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Sep 2009
Posts: 17,765
Liked 1374 Times on 1332 Posts

Sounds to me like the only variable not accounted for is the actual extract from the DME did not equal the potential extract values. Your numbers all add up.

03-23-2010, 07:23 PM   #5
RushN24
Recipes

Jan 2010
New Jersey
Posts: 124
Liked 2 Times on 2 Posts

Thanks guys for the suggestions, I'll review my notes and try to see what happened. I used Beersmith too, and the run-off sample I cooled down to 95F. I read 1.044 on the hydro and adjusted to 1.049 using Beersmith. I guess I had to have messed up somewhere in measuring the sample gravity, it's the only thing I can think of.

Quote:
 Originally Posted by Reelale Sounds to me like the only variable not accounted for is the actual extract from the DME did not equal the potential extract values. Your numbers all add up.
See that's the conclusion I keep coming to is I was somehow inefficient in my use of the DME. But, I had one prepackaged 3lbs bag and 1 prepackaged 1lb bag to make up the 4lbs so I could not have messed up in weighing it out. Doh idk.

I'm not worried about the quality of the beer, in fact it looks and smells awesome. My concern is more that I designed my recipe based on 67.5% efficiency which I thought I came relatively close to after measuring the run-off gravity, but with the measured OG I got my efficiency according to Beersmith is only 48.5%. Not only is that low but I want to be able to estimate the proper efficiency for my system and I don't feel comfortable using 48.5% for my next recipe even though that is what the numbers point to. I just want to figure out what went wrong so I can be more careful next time you know?....Thanks again
__________________
“Filled with mingled cream and amber I will drain that glass again. Such hilarious visions clamber Through the chambers of my brain -- Quaintest thoughts -- queerest fancies Come to life and fade away; Who cares how time advances? I am drinking ale today.”

-E.A. Poe

03-24-2010, 01:58 PM   #6
ezerhoden
Recipes

Sep 2009
Pittsburgh, PA
Posts: 63
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This is common when extract is added to a batch. The heavier wort sinks to the bottom and your hyrdo reading is low. Unless the wort is mixed very well your reading will be off. If you know your gravity from the mash then your gravity after the extract is exactly what you figured in your calculations.