Missed OG by 10 points!!!! Over-sparge to blame?

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BootsyFlanootsy

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Made a 5gallon batch tonight. OG was supposed to be 1.062. Preboil gravity was 1.044 which by my calculations with a 60min boil should have given my a post boil gravity of 1.057, ( this is before the addition of 12oz's of invert sugar at 15mins, which theoretically should have brought me up in the ballpark of my calculated OG),. However I wound up with an OG of 1.052!! WTF?!?

So I started thinking, I miscalculated my sparge water addition. I should've only added 4.61 gallons, but would up adding about 5.25. I overcollected by about a gallon.


My initial guess is this could be a big part of the culprit.


Curious what those more learned in the ways have to say about this...
 
seeing that my pre-boil gravity was 1.044, I calculated 6.5 x 44=286. then 5gallons post boil so 286 divided by 5 = 57 giving me 1.057 OG - my late addition of invert sugar. putting me right close to the mark... at least in theory.
 
You either had a poor sparge (not extracting enough of the sugars), poor mash efficiency or bad hydrometer readings. Did you take the gravity of the final runnings of your sparge? Gravity by refractometer or hydrometer? If hydrometer, did you correct for temperature?
 
yeah Hydrometer. No, I didn't take a gravity reading until both the first runnings and the sparge were combined.

Guess it's time for me to bone up and buy a refractometer.
 
According to the formula:
preboil GU x preboil volume = postboil GU x postboil volume

your calculation of SG=1.057 before the sugar addition is correct...

Are you sure you measured your preboil and postboil volumes accurately? How are you measuring the gravity? Maybe your refractometer is not reading consistently (I recently noticed mine isn't, much to my surprise), or alternatively your hydrometer sample wasn't cooled to 60F.

Edit: while writing I see you measured with a hydrometer... note my comment about my refractometer above... maybe it's not reading consistently because it's a chinese $15 job.
 
Rough estimate with BeerSmith, when starting with a 1.044 gravity with 6.5 gallons, your final gravity with 5 gallons minus the 12 oz sugar would be 1.054. Are you sure your volumes are correct?

A 60 minute boil with 6.5 gallons typically won't get to 5 gallons. Is your process repeatable to go from 6.5 to 5.0 gallons in only 60 minutes? I typically only lose 1 gallon in an hour, but everybody's set up is different.

Using the same calculation with the sugar added and 5.25 gallons post boil gives: 1.044 preboil, 1.052 post boil.
 
If I had to guess I'd say you had less than 6.5g preboil and slightly more than 5g post-boil. 6 gal preboil and 5.1g post-boil would come out 1.051.
 
tre9er-


you are spot on sir. I just ran the numbers and that is precisely what happened. OK, this is very valuable to know, thanks everybody!
 
though now that I'm sitting here thinking about it, I STILL over-sparged and collected one gallon too much. I filled the pot damn close to the point of aaaaaalmost being TOO much. I also just noticed I had planned for this to be 5.25 gallons into the carboy, my mash addition was 4.12 gallons and I collected nearly 3 gallons of first runnings. For the sparge I was supposed to add 4.73gallons and I added more like 5.5gallons. I also effed up by calculating for a 75 minute boil @ 7 gallons of preboil wort. UGH.


Ok. time to rerun the numbers as I know am getting a better feel for where they actually are.
 
Trust me, I had issues last night and was guesstimating all over the place. I was at 1.055+ after my boil and just tossed the hydrometer in the fermenter and started adding pre-boiled/cooled water while stirring. I stopped around 1.040.

I found that I panicked and forgot all of the best-laid plans I had to carefully measure things and be methodical. Not enough bottle-conditioned homebrew was part of the problem :mug:
 
UGH, this is really starting to get me worked up. I just brewed a Patersbier yesterday. Simple, low gravity, pale ale.

Targeted OG was 1.047. I did a multi-step infusion mash. AGAIN my pre-boil gravity was spot on, if not a point high. I took the sample at about 210f, just before the boil got rolling, chilled it to about 80, got a pre-boil gravity of 1.030 which when temperature adjusted gave me a gravity of 1.033. which when calculated with 6.37 pre-boiled wort x 33 = roughly 210. Factoring in a 90 minute boil which should leave roughly 5 gallons post boil, this would give me in the ballpark of 1.042. I added 12 ounces of sugar at 10mins and with that taken into account I should have hit my target OG spot on at about 1.047 or 1.048.

I was careful to plan my infusions this time around and wound up with roughly 3 cups too much wort, which I can't imagine would cause what I found my actual OG to be when I measured post-boil....

1.041!!?!?!?!


Color me flumoxed.
 
I'm having the opposite issue - I'm overshooting my OG by as much as 15. My issue is poor volume management. I need a better way to calibrate my volumes.
 
at least there is some sort of constant here I guess....

the problem I'm having can easily be condensed to this:

Though Pre-Boil Gravity is correct, post boil gravity is about 8 points too low, consistently.
 
The only variable should* be volume, right? How do you measure that? And is it corrected for temp? Also, and you might have covered this, you're cooling your samples right (below 90F)?

(although, I ran a quick calc on a typical 1.050 OG beer losing about 20%ish per hour, and assuming 4% expansion of liquid from room temp to near boiling, and if you don't adjust for temp it actually would cause you to overshoot your OG by 2 pts or thereabouts)
 
Would incomplete mixing of first and second runnings possibly give inaccurate pre-boil gravity? That wouldn't make sense if you're taking the sample out after the water is almost boiling because the heat should mix things up, but is that a possibility?
 
Mix your wort thoroughly post sparge/pre boil. Verify volume. Take gravity.

Verify volume post boil. Take gravity.

This whole problem looks like a volume issue.
 
thanks for the multitude of input folks, it's greatly appreciated.

I'm definitely cooling samples to below 90f.

I did a multi-step infusion mash this time around, so initially i mashed in with 2.60 gallons @1.33q/lb for 1st infusion, hit my target temp of 148f. Mashed for 90 mins, ( which I've been doing just to be safe), then I added 3.2 gallons of 170f water to bring the mash up to 158f for 20mins, and lastly I added 6.7q of 212f water which brought the whole mash up to 168 for 10minutes, after which I began vorlauf. During the main mash I stirred 2-3 times, and stirred well at each subsequent addition. The grain bed settled well and vorlauf was a fairly easy one with a relatively clean wort right out of the gate.

So to recap, I used roughly 7.4 gallons of water, lost somewhere around abouts a gallon to the grain and the mash tun. I collected about 1liter over what I was aiming for in retrospect, so instead of 6.4 I collected a liter over that.

So the problem still remains, why on earth would all seem well at the beginning of the boil, in regards to gravity, and then be so off by the end?

It seems to stand to reason that if your pre-boil gravity is right where it ought to be, than the post-boil should wind up where it needs to be as well.
 
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