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Mashing issues using BeerSmith

rjreusch

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I made my first all grain batch using BeerSmith software. I make roughly 5.5 gallon batches. I collected over 1 gallon more wort from my mash, mash out and sparge than the software predicted. Not sure how it's possible the grain wort absorption could be that much less. I must have measured water and grain about right because I hit my target mash temp right on. I got about an 85% mash efficiency as well. Anyway there doesn't seem to be a way of changing the amount of water absorbed by the grain..it is fixed in the software. All other ways I have tried to use to approximate what is happening make the software very cumbersome to use. When don't check the "calculate boil volume" tab then it tries to increase my mash/sparge water to reach the boil volume I put in. Can anyone point me in the right direction? Thanks.
 
First, make sure you have all of your water losses for dead space and trub loss correct in your mash profile. 

Second, you say that you got 'roughly' a 5.5 gallon batch and collected 1 gallon more wort.  You will need to be more precise if you are going to get the software to better predict what your process produces. 

Third, Volume losses occur in other places than grain absorption.  You have dead space from your mash tun, boil off rate, loss to chiller and trub (your ~1 gallon extra wort), and any sampling loss both before and after brewing.  You can make a preliminary adjustment based upon your initial brew, but I would recommend carefully measuring the volume of water in (both mash and sparge), volume collected before boil, post boil volume, gravity pre-boil and gravity post boil.    From these you can calculate the losses in your mash tun (water in - volume out [corrected for temperature]) to give you your grain absorption.  Then you can figure out your boil off rate (pre-boil volume - post boil volume -- both corrected for temperature).  As an added check to your figures, your pre-boil gravity points (volume x specific gravity) should be pretty close to your post boil gravity points (same calculation).  Mine usually come out within 1%, which is about my measurement error.

The boil off rate you can adjust in your equipment profile.  The grain absorption rate can be adjusted in 'Options' >> 'Advanced' >> 'Grain Absorption'.

I would check these numbers over the next few batches and then make an adjustment to both based upon either the average for the batches measured or the median value for the batches measured, which is better to use if you have one skewed batch.
 
Thanks, I agree with all you say. I will proceed with caution. I didn't know the advanced feature of changing the water absorption. I am just finding it incredible that I recovered 9.37 gallons of wort (160F) from 14.44 lbs of grain and 10.585 gallons of mash, mash out and sparge water. It is below the grain adsorption estimate and anywhere I've looked. I thought for sure a mistake on my part. I rechecked the calibration I did for checking volume in the kettle and confirmed I did collect about 9.37 gallons of wort. If I was significantly under the weight of grain (very unlikely) or used more water than I thought I measured, I surely would not have hit my target mash temp right on like I did. It just makes me more nervous going into my next brew and not very confident I will know what will go into the kettle.
I also had a very, very high evaporation rate but this can be explained I think by the dimensions of my kettle where I have a very high surface area per volume. I guess I just don't like major surprises on brew day!
 
Remember that your 9.37 gallons at 160F is actually about 9 gallons at room temperature.  If you are making a 5.5 gallon batch (into the fermentor) that's a really lot of water to start with.  Given a typical 15% evaporation rate, you still would have around 7.6 gallons post boil.
 
Yeah I wasn't expecting that much wort, it still makes no sense to me.
 
If you export your recipe in bmx format and post it here, I can look at it and see if anything stands out.
 
OK file attached (I think)
 

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  • IPA.bsmx
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How sure are you of your gravity readings, both pre-boil and post-boil? 

Since you are fly sparging, your grain absorption really does not factor in, except for figuring out if your volume fits within your mash tun.

It looks right now like you over sparged, which diluted your pre-boil gravity reading.  When I look at the gravity points predicted (31.27 liters x 51 points = 1626 gravity points [sorry, I work in liters, so BS automatically converts]) versus gravity points attained (35.49 l x 47 points = 1668 gravity points), you are pretty close to where you wanted to be, but with additional water diluting your preboil gravity.

When fly sparging (I don't, but have been with people who do), typically, the kettle or measuring stick is marked and the sparge cut off when the desired volume is reached.  This may fix some of the additional preboil volume you encountered.

What does not compute is your post boil volume/gravity.  When I figure your pre boil points (with shrinkage taken into account) I get (35.49/1.04 [expansion factor] x 47 points) 1603 gravity points.  Post boil figures is 18.93 liters (kettle) + 3.79 liters (kettle loss) = 22.72 liters at 48 points is 1090 gravity points.  This is a great disparity which indicates that either there is a loss in volume you are not accounting for or your gravity or volume readings are off.

 
Some of my post boil info was not entered right causing some confusion...sorry. First use and struggled some. One thing I am going to do gleaned from what you said is to put the grain absorption figure back to default and set my evaporation rate at 15% for starters. I will then measure as I'm collecting wort and stop at the pre-boil volume given by Beer Smith. Like you said this may prevent some over sparging and collecting if I do indeed have very low grain absorption. I will have to see what type of mash efficiency I have with this change and be prepared to adjust the pre-boil gravity if necessary. With my high evaporation rate I may also need to add water prior to the end to reach the correct batch size and gravity points. Once I do another batch or two I will have a better feel for those things and can make more adjustments. This si a work in progress and I appreciate the help from an experienced user. Sorry I couldn't grasp everything you were pointing out.
 
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