How to calculate PreBoil Gravity

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BrokenArmBrewing

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I've been stuck with some pretty bad efficiency lately, and I'm trying to hone on what might be going wrong. I use QBrew software, but it doesn't calculate PreBoil gravity. Any Ideas how to calculate this???

I'm thinging if I miss this, I could always boil down a quart or so more. Less volume is not what I'd like but . . .
 
Well It was supposed to be a Terripan Rye Pale Ale, but someone forgot to order the magnum hops -_- So, Amarillo for the bittering instead . . . Oh Well
 
pre-boil volume = 8 gals
pre-boil gravity = ??
post-boil volume = 6 gals
post-boil gravity = 1.050

So, to calculate pre-boil SG for a 1.050 target OG would then be:
(post-boil volume/pre-boil volume) x (post-boil gravity -1) =
(6/8) x (1.050-1) = .75 x .05 = 0.0375 +1 = 1.038 rounded up

I think:confused:
 
I worked that link....looks like i was at 70% efficiency ..... I don't know how to get it better . . . . bigger mash tun?? There's one a 10 gallon at Lowe's now for 40 bucks....I work there, so it may suffer some "missing pieces" for a better price ...lol...don't need that spigot any way
 
Spend $30.00 and get a decent refractometer, and you won't have to calculate anything. They are perfect for preboil gravity readings!
 
70% efficiency is good using a cooler tun (anything between 60-75% is good/normal). I use a 10 gallon cooler for my tun and its perfect for my 5 gallon batches. I did a brew last weekend that had 20lbs of grain and 8 gallons of strike water, with a little room to spare even (though not much...)! What size batches are you doing?
 
2 hours later and I've got some ambitious yeast! Consistent airlock activity. Was a washed California 2 in a 2 liter starter. So far happy!
 

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