So I cant figure this out

[ryan0914]

I took a pre boil gravity reading for my imperial stout i was making today and then forgot my final gravity reading. So at 13 Gal i was at 1.070 and beer smith said i should of been 1.058. Post boil I was at 7.5 so what should my gravity have been. I also don't understand how I had such a high efficiency. i screwed up the mash. I mashed at 155 for about 30 min and then i had to add a little heat and then my regulator screwed up and didn't turn off. It stayed on very low and brought the temp up to 162. I and let it sit for another 30. I figured it would be fine just a lot of unfermentable sugars, but I didn't think i would get so high efficiency with such a high mash temp.
can anyone explain all this to me. I thought I understood all of this pretty well, but this is messing with me.

 

[northernlad]

You boiled down to 7.5 from 13 gallons? Based on what you said, you are sitting on a 1.121 OG. TO find this you take the volume of the preboil (13) and multiply by the gravity minus all the decimals, etc (70) to get what I call the First wort gravity (910). THen divide by your post boil gravity (7.5) to yield your OG (121) or 1.121 I hope you used a shytload of hops and pitched a shytload of yeast.
You didn't screw up the mash you got great efficiency.

 

[OLDBREW]

First thought would be are you sure you mixed the pre-boil volume extremely well, or did you just open the valve and grab a sample from the tap. Reason I ask is that if not mixed very well, you can have a false pre-boil SG reading (higher or lower) depending where in the kettle the sample came from.

Secondly.. It is hard to determine the OG without knowing the exact volume (boiler loss included) after the boil. So if you left 1/2 gal. behind in the boiler, and only collected 7 1/2 gals. into the fermenter, the volume is really 8 gals., not 7 1/2 gals.

The third is a question on your systems evaporation rate as in gals. per hour, and how many hours did you boil the wort for?

 

[twoodward15]

Also, did you correct for the temp of the wort when you took the reading?

 

[ryan0914]

Wow ya it was only supposed to be a 1.096 oh well. Ya I did a pretty hood abount of hops and a 1600ml starter of wlp001 and a pint of a cake from Cali V. So I was thinking that should be enough. I wasn't expecting such high effiency. Has anyone else had a problem with beer smith not adding up sugar additions correctly.

 

[northernlad]

Wow ya it was only supposed to be a 1.096 oh well. Ya I did a pretty hood abount of hops and a 1600ml starter of wlp001 and a pint of a cake from Cali V. So I was thinking that should be enough. I wasn't expecting such high effiency. Has anyone else had a problem with beer smith not adding up sugar additions correctly.

Beersmith is a calculator, it does what you tell it.

 

[ryan0914]

well for instance the only thing that i can think to why my efficiency was so off was the candy sugar and molasses I added. 2lb candy .5 molasses. maybe that is why i am showing so high. I took gravity after I added all my sugars.

 

[OLDBREW]

huh!
Why would you not put sugars added to the recipe to be calculated?
Doesn't BeerSmith calculate the sugars as 46 points, per pound, per gallon. and Molasses at 36 points, per pound, per gallon when you build your recipe?

And how long did you boil this recipe to lose all that volume to evaporation, or is this a big secret?

 

[ryan0914]

well on they were added to the recipe and beer smith did the calculations and everything. i was just wondering if it may be doing to wrong. I do BIAB and wasn't expecting such high efficiency with 18 LBS of grain and 13gal of water I was about an inch from the top of my pot. so that was the extent of my pot. I added 2 lbs of candi sugar and half lb of molasses and one can of LME. Its no secret i boiled pretty hard for about 2 hours or so. and as i look back i was at about 12 gal post mash instead of 13. and

 

[Northcalais40]

I think part of the confusion here is that 13 gallons includes the amount absorbed by the grain. Like,what .15 gallons per pound of grain? If I'm correct (I'm guessing), you could estimate the preboil volume to be 13 gallons-(.15gal/lb*18lb). Then do the math printed above to back out your estimated post boil gravity. QED