I conquered my first all-grain batch this weekend, and after some early problems constructing my cooler mash tun, it went off without a hitch.

It's a Northern Brewer all grain kit, and the recipe called for 9 lbs Belgian Pils Malt. The mash technique called for 160 degree water to be added to the grain and a 1 hour rest at 147 degrees. The mash wound up being just below 150 degrees for one hour. Then, we sparged and boiled.

Two things happened here. First, in an hour, the wort reduced from 6 gallons to just over 3 gallons. No biggie here - we topped it off to 5 gallons, mixed well, and measured.

The OG was 1.060. The expected OG is 1.045. So, either we got 98% efficiency (according to Beer Calculus - http://hopville.com/recipe/826498/belgian-specialty-ale-recipes/patersbier ), or something odd happened on our way to beer.

I pitched the yeast anyway, and now it's in my fermentation cooler at 67 degrees.

Anyone have any idea what I did here to get such a high gravity?

1 Answer 1


I'd bet that you didn't get it as well mixed as you think you did and you got a false reading. I've seen it happen many, many times. The other thing to address is your boiloff amount. You should be boiling off maybe 1.5 gal. in an hour. Boiling off 50% of your wort needs to be addressed.

  • 2
    True enough - by "no biggie" I meant less that I didn't consider it a problem that needed to be addressed next time, only that I wasn't really sweating that as part of this particular problem. I'm relatively sure we were boiling at too high a temperature - first time all-grain/propane burner noob mistake.
    – Ell
    Aug 22, 2011 at 18:57
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    Minor nit here...boil temp is always the same. You were boiling too vigorously, not at too high a temp!
    – Denny Conn
    Aug 23, 2011 at 15:30
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    Fair enough! Thanks for the tip and correction. Just to be clear, though, I solve the problem of too vigorous a boil by lowering the heat, correct? (not intended sarcastically in any way to say I'm correct, just checking to make sure).
    – Ell
    Aug 23, 2011 at 21:43
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    Lowering the heat of the burner doesn't actually affect the temperatue of the boiling wort -- it will always be at boiling temperature, 212 F, plus or minus. It will change the evaporation rate though. Less heat means less evaporation. Also, the shape of your kettle will affect evaporation. More surface area for the wort will increase the rate of evaporation. Aug 24, 2011 at 3:30

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