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Brewing Topics => All Grain/Advanced => Topic started by: murddog on January 23, 2021, 05:29:37 PM

Title: Perfect post-mash gravity, low pre-boil gravity
Post by: murddog on January 23, 2021, 05:29:37 PM
Hello everyone,

Relatively new to beer smith but I've done a few all grain brews using the program. The only 2 brews I've done have had perfect post mash gravities. However, after I sparge, and take a preboil gravity, I get a very low gravity reading compared to the estimated preboil gravity on the program (roughly 6 gravity points low). I've noticed that beer smiths post mash gravity and preboil gravity are exactly the same? How could this be since sparging involves diluting the original post mash wort? I end up with a much lower alcohol beer because my original gravity is substantially low (approximately 7 gravity points).

I've included images of my session targets. Thanks guys!

Michael
Title: Re: Perfect post-mash gravity, low pre-boil gravity
Post by: BOB357 on January 23, 2021, 07:03:09 PM
The post mash gravity reading is taken after the sparge, and should be the same as the pre boil unless you top off with water or add fermentables between the two readings. It appears that, for whatever reason, your mash efficiency was lower than predicted.
Title: Re: Perfect post-mash gravity, low pre-boil gravity
Post by: Kevin58 on January 23, 2021, 08:37:59 PM
You misunderstand post mash. It is taken AFTER sparging. And yes, it is the same as pre-boil gravity Unless you are adding top up water, sugar or other fermentables to the boil kettle.