Author Topic: Preboil Gravity off  (Read 2486 times)

Offline chadchaney97

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Preboil Gravity off
« on: March 16, 2013, 11:49:11 AM »
My preboil OG is consistently off by about 10, example 1.040 is 1.030, etc.  Always seems to roll this way, nay ideas?

Offline duboman

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Preboil Gravity off
« Reply #1 on: March 16, 2013, 12:19:49 PM »
Things to evaluate:
Crush quality
PH
Water to grist ratio
Temp
Sparge method
Sparge temp
Equipment-bazooka screen, manifold, false bottom?

Maybe tell us your process and can chime in accordingly
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Offline tygo

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Re: Preboil Gravity off
« Reply #2 on: March 16, 2013, 01:00:38 PM »
Is your actual efficiency relatively consistent?
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Offline hellbound

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Re: Preboil Gravity off
« Reply #3 on: March 16, 2013, 01:45:42 PM »
Things to evaluate:
Crush quality
PH
Water to grist ratio
Temp
Sparge method
Sparge temp
Equipment-bazooka screen, manifold, false bottom?

Maybe tell us your process and can chime in accordingly

+1
It sounds like just poor efficiency, could be attributed to alot of things.
Dave
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"Been drinking all the beer I can find since 1982"

Offline duboman

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Preboil Gravity off
« Reply #4 on: March 16, 2013, 02:25:30 PM »
Is your actual efficiency relatively consistent?
+1
If this is a consistent issue you can change your efficiency % and just add some grain to your recipes as well!
Peace....Love......Beer......

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Offline wort-h.o.g.

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Re: Preboil Gravity off
« Reply #5 on: March 16, 2013, 02:46:35 PM »
My preboil OG is consistently off by about 10, example 1.040 is 1.030, etc.  Always seems to roll this way, nay ideas?

Do you crush or received crushed grains? Kits can come a little coarse and hurt efficiency.

What is your mash process- qt/lb, batch or fly sparge, single infusion...etc.

Offline stephanehml

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Re: Preboil Gravity off
« Reply #6 on: April 12, 2013, 05:03:46 AM »
My preboil OG is consistently off by about 10, example 1.040 is 1.030, etc.  Always seems to roll this way, nay ideas?

Take your gravity at 20°C, not at 100°C.

Offline wckedpete

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Re: Preboil Gravity off
« Reply #7 on: April 13, 2013, 03:00:44 PM »
If you were hitting the gravity before and now magically you are not, I would check the milling of your grain first. If you have never hit your gravity, it could be your system.

Offline euge

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Re: Preboil Gravity off
« Reply #8 on: April 14, 2013, 04:42:05 AM »
My preboil OG is consistently off by about 10, example 1.040 is 1.030, etc.  Always seems to roll this way, nay ideas?

Take your gravity at 20°C, not at 100°C.

+1

Also, I've found a preboil gravity reading to be utterly useless and a complete waste of time.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline jimrod

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Re: Preboil Gravity off
« Reply #9 on: April 14, 2013, 11:44:45 PM »
Crush quality
PH
Water to grist ratio
Temp
Sparge method
Sparge temp
Equipment-bazooka screen, manifold, false bottom


I had the same problem and was very careful to correct all of the above. Then I got rid of the bazooka screen and added a false bottom and it changed everything. Gained 10 pts.
The liver is evil and must be punished

Online AmandaK

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Re: Preboil Gravity off
« Reply #10 on: April 15, 2013, 07:41:34 AM »
My preboil OG is consistently off by about 10, example 1.040 is 1.030, etc.  Always seems to roll this way, nay ideas?

Take your gravity at 20°C, not at 100°C.

+1

Also, I've found a preboil gravity reading to be utterly useless and a complete waste of time.

Really? Why?

Also, have you checked your hydrometer's calibration in water?
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Offline gsandel

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Re: Preboil Gravity off
« Reply #11 on: April 15, 2013, 08:29:23 AM »
I haven't figured out what in beersmith tweaks that pre-boil gravity number.  Mine is consistantly off by about 10 points (I always have a higher number than BS says I should), but end up within 1-3+/- of my original gravity target and I don't run off 15.57 gallons in my 15.5 gallon keggle as it tells me to (so it is not at all concerning).

I figure for me it is a combination of the equipment settings in BeerSmith, (it doesn't have a keggle setting), an estimation of what my deadspace in the mash tun is (I never checked), and that for whatever reason, my vigorous boil does not evaporate at the same rate that BS thinks it should....(I am at altitude, but I would figure my boil off rate would be higher, not lower, but boil temp is lower here, too).

At any rate, I feel like hitting your expected pre-boil gravity is an indication that you have done everything properly and all systems are go!
You wouldn't believe the things I've seen...

Offline euge

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Re: Preboil Gravity off
« Reply #12 on: April 15, 2013, 12:36:50 PM »
The problem with a preboil gravity reading is that if your water volume is off then most likely your numbers will be skewed. But, this doesn't necessarily mean that the final numbers will be off.

I've found that the most beneficial gravity reading is at flameout and when it is certain that the desired and expected volume is correct. 
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Online goschman

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Re: Preboil Gravity off
« Reply #13 on: April 15, 2013, 12:44:52 PM »
I take a preboil gravity reading for every batch since I know exactly what my preboil volume is. When I take my post boil gravity I can calculate the exact post boil volume thus getting a more accurate efficiency. My buckets are only calibrated in 1/2 gallon increments so I like to know my post boil volume more accurately...

Offline klickitat jim

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Re: Preboil Gravity off
« Reply #14 on: April 15, 2013, 01:02:48 PM »
I use refractometer for first run, start boil, end boil, then a hydro reading of what ends up in the fermentor.

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