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-   -   Og (http://www.homebrewtalk.com/f13/og-23720/)

roggae 03-04-2007 12:45 AM

does gravity rise as you boil the wort? like pre-boil OG versus post boil OG. is there a difference?

i only ask as i have recently begun taking readings. i have brewed what i thought was good beer for about a year and now i am finding i am missing my gravity by like .02-.04...'d think my crush was good(maltmill at LHBS). i am using a wort-hog converted cooler mash tun, a converted keg kettle, and a hurricane burner.

at a loss, but conted nonetheless...

roggae 03-04-2007 01:10 AM

is it at all feasible that i am getting like 50% eff? i mean i never knew what iwas getting, but now that my brewmate is all about #'s it seems this is what we are getting...!?!?!?!?

uwmgdman 03-04-2007 01:16 AM

Post your recipe and gravity calculations (include volume measurements) and it would be easy to calculate your efficiency. Is it possible you're only getting 50%, very possible if even one element of your process is out of whack.

Blender 03-04-2007 01:20 AM

We would have to have the recipe to supply an efficiency number. I think it is possible to get 50% efficiency but it depends on how you measure it. I prefer to measure the gravity before pitching the yeast, some go by the gravity before the boil.

roggae 03-04-2007 02:10 AM

17 lbs maris otter
1.5 lbs melanoidin
1.0 lbs 60 L

simcoe hops at 60, 30, 15, 10, 1

mash at 150 for about 90-100 mins

boil 90 mins

any thoughts?


uwmgdman 03-04-2007 02:21 AM

What was the volume of the beer in the primary? 10 gallons? What was the OG of that wort in the primary?

roggae 03-04-2007 03:27 AM

never mind. i figured it out. thanks all!

knipknup 03-04-2007 02:10 PM


Originally Posted by roggae
never mind. i figured it out. thanks all!

Please post what you found in case it helps someone else in the future. I'm curious...

roggae 03-04-2007 02:42 PM

i took my OG post boil pre-pitch and i was in my target range. i took an OG of the first runnings and i was dead on. then i took a reading of the first and second runnings and i was waaaay under. i allowed wort to boil for 90 mins and the reading obtained was 1.085. so i was a little lower than i had hoped, but i was much closer than i had anticipated after the pre-boil gravity....


david_42 03-04-2007 02:49 PM

The gravity of each running decreases, there is less sugar left in the mash. Your first running should be 50% higher than your TG (adjusted for temperature), the second a little below, the third maybe half. The last running for batch sparging will be higher than the cutoff for fly sparging. When brewers made separate brews from each run, they made a barleywine, an ordinary and a small beer.

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