All Grain 10 Gallon Batch - Need help with BS2 setup

First let me say, I'm new to AG brewing and BS in general. I am trying to set up my BS2 for future batches which will all be 10 gallons.

Im having trouble getting BS to adjust my grainbill to compensate for my lauter tun deadspace and trub losses. (lauter tun deadspace: .75 gallons with a 70 qt plastic cooler)(trub 1.75 gallons - using a 15.5 gallon ss keg as boil pot and this is the volume left in the keg, after all liquid runs out of the ball valve)

I have set up my equipment profiles and mash profiles (single infusison, batch sparge)

I though I had it all figured out, but I just brewed last night and missed my OG by a lot (Target 1.073 and actual 1.062)

I know the big problem is water volume vs grain bill (because of the amount of "extra" water that was left in the boil pot, when I filled both my 5 gallon fermenting buckets) but each time I enter a new recipe with my existing equipment, I dont have a good way to adjust the gain to reach the target SG.

I tried entering a new equipment profile with the deadspace and trub loss, set to 0 and then entering the recipe initially with this profile, then scaling the batch (using same 10 gallon batch volume) to use equipment profile with actual deadspace/trub loss. but the change is not drastic.

Is there a better way to figure out the extra grain needed to achieve the needed target OG when using my system with known deadspace/trub loss.

I am trying to avoid increasing the entire batch size because the water measurements will also change and I fear, cause more problems.

Here are my settings if needed:

Equipment:
Brewhouse Efficency: 72%
Hop utalization: 100%
Mash Tun Volume: 17.5 Gallons
Mash Tun Weight: 10.0 lbs
Specific Heat: 0.3
Lauter Tun Deadspace: .75 gallons
Top up kettle volume: 0
Boil Volume 12.91
Boil time : 60 min
Boil off: .69 Gallons (5.3%)
Post boil volume 12.22
shrinkage:4%
Loss to trub: 1.75 gallons

Water to grain ratio: 1.250 qts/lb

Grain Absorbtion calculated: .92 fl oz/oz grain (changed in advanced options)

Any info would be great. Thanks and sorry for the long post.

Don't know enough about BS2 or AG stuff to help. But I am interested in your problem as it would provide info on manipulating BS2. Could some knowledgeable individuals chime in for us! Thanks.

Beersmith will do the math for you.  But, you have to get the input parameters correct first. 

Is your MLT deadspace truely deadspace?  MLT deadspace is space below the dip-tube that is NOT occupied by grain.  there's been a lot of discussion recently here about this definition. 

What is your MLT configuration?  Do you have a false bottom, or a manifold?  If you don't have a false bottom, then your deadspace is not truely deadspace.  You are probably better off using 1/4 - 1/2 the water test figure.

What was your ACTUAL efficiency for the batch?  Your profile lists "brewhouse" efficiency, but I'm more interested in your MASH efficiency because THAT drives your OG more that "brewhouse" does.

That boil-off is pretty low.  I shoot for 12% / hour.  Is that measured ACTUAL or estimated? 

Do you take temperature, gravity and volume measurements at each step in the process?  Can you post the measurements you have?

- First runnings
- All subsequent runnings
- Pre-Boil
- Post-Boil
- Into fermenter(s)
- Actual volume left behind in boil kettle

I'm asking these questions to be sure that we aren't dealing with a mash efficiency issue instead of a water volume issue.  The above are critical to pinpointing the source of the problem.  I (and others) can help, but we need to be able to see which step of the process isn't adding up to be able to tell you which adjustment needs to be fixed.

There is a little bit of quick math that you can do....

You missed your target by 11 points in 12.22 gallons (post-boil).  If you multiple points by gallons, you get a total of 134 points (of needed sugar to raise the gravity to the desired level).  At 34 points per pound of grain....that's just under4 lbs of additional grain needed. 

That's a quick and dirty approach that doesn't take some variables into account.  But, it will certainly get you within a couple of gravity points.