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Gravity Calculation Issue

RatBait757

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Here is a screen shot of my recipe.  The strange part is that the Pre-Boil gravity is HIGHER then the POST-BOIL gravity.    Doesn't make sense.  Has anyone else encountered this?



 
What would make it really clear is your volumes tab.  From what I see right now, I am guessing that you are boiling for 60 minutes and then topping off the fermenter to achieve your desired final volume.  The post boil gravity takes into account this top off water. 

If I am all wet with this reading, let me know.  The best way to get help in the future is to save the recipe as a .bsmx file and post it with your question.  This way, it is much easier to diagnose without having to try to figure out what is missing.

 
Oginme,
Thank you for the quick reply.  I've been dealing with this for a while and just putting up with it.  So glad I found this forum.  I have attached the file.
 

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  • Kinas NEIPA.bsmx
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OK, I found the issue. 

Go to your equipment profile and under the 'boiler' section there is a box for 'Calculate boil vol automatically' 

Currently you have this unchecked which means that the program takes your values as fixed volumes and does not adjust them according to the recipe volumes.  While not specifically stated in the 'vols' tab, there would need to be some top off water at the end of the boil in order to end up with a hot volume of 23.09 liters (sorry, I work in metric) lose 0.92 liters to cooling shrinkage and then 2.84 liters to trub and come out with 23.02 liters in the fermenter. 

You need to check this box for the program to calculate the needed water requirements for you.  While you are at it, I would also check the box for 'use boil off as hourly rate' in case you decide to change your boil times so that the program will react to the increased/decreased boil off due to a different time of boil.

Making these changes will fix your issue.
 
I've been struggling with a similar issue - in the equipment profile, is the "Batch Vol into the Fermenter" before or after adding the post boil top up water?  Logic says that the batch volume is volume with the top up water, however when I do a manual calculation we're not even close. If I need to top up in the fermenter, is my projected OG before or after the top up water?  Sorry if this is a basic question!
 
Fermenter volume includes all the liquid from the boil PLUS any top off water indicated in the recipe.  It will NOT include the starter volume if you add that to the fermenter and indicate such in the software.  If you go to the 'vols' tab in your recipe, you can follow the volumes through the process and compare them at any step to actual measurements to see where the model may deviate from actual recorded volumes.  From there, you can better pinpoint which variable in your equipment profile may be off.
 
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