Ss Brewing Technologies Giveaway!

Home Brew Forums > Home Brewing Beer > All Grain & Partial Mash Brewing > Low OG after boil...
Reply
 
LinkBack Thread Tools
Old 01-30-2011, 09:17 AM   #1
Aloha_Brew
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: Mililani, Hawaii
Posts: 90
Default Low OG after boil...

Okay, so this is my third all-grain batch i just completed up to fermentation. All three were done very much the same. Boiled water beforehand or filtered it before letting it cool to a temp around 150 for the mash with grain in the bed. This recent batch I kept around 152.

Here's the grain bill:
7 lbs Pilsener
4.5 lbs 2-row
2 lbs Munich
1 lbs Wheat
.5 lbs Peated
.25 lbs Carafa III

I used a little less than 9 gallons total for mash and sparge, adding some extra water during the 90 minute mash to keep temps up. My total yield was about 7 gallons.

After boil I yielded about 5.5-6 gallons. Oh, I also added 1oz Northern Brewer at 90 min, and again at 30 min, with 2oz Fuggles at 5 min. And Irish Moss and nutrients were added also at 5 min.

With my 2 previous batches I met expected OG; one being as high as .08. However, this time my OG was expected at .079 but was actually .05. Now, these homebrew calculators are alot smarter than me and the only way I can make myself get .05 after boil is if my yield was 8 gallons...which my 7.5 gallon pot just can't do with more than that even before boil.

Any ideas why my OG is so low? I can only figure I should have measured OG before boil to make sure I got enough concentrated yield from the mash. Otherwise, the only other possibility is I didn't boil long enough. But why just this batch???

__________________
Aloha_Brew is offline
 
Reply With Quote Quick reply to this message
Old 01-30-2011, 11:35 AM   #2
MalFet
/bɪər nərd/
HBT_LIFETIMESUPPORTER.png
Feedback Score: 1 reviews
 
MalFet's Avatar
Recipes 
 
Join Date: May 2010
Location: NYC / Kathmandu
Posts: 8,208
Liked 1232 Times on 819 Posts
Likes Given: 561

Default

You don't mention anything about your mash or sparge setup, and these factors are probably more important to this question than your particular grain bill. Also, 2 gallons is a fair bit of loss during mashing...is that standard for you?

All that said, my gut instinct is to check your grain crush. Consistent across all three batches

__________________
MalFet is offline
 
Reply With Quote Quick reply to this message
Old 01-30-2011, 06:17 PM   #3
Aloha_Brew
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: Mililani, Hawaii
Posts: 90
Default

I got a standard cooler that can hold about 10-12 gallons. I have a small analog thermometer I place in the middle of the mash. To maintain temps for 90 minutes I usually end up adding 1-1 1/2 gallons. My method of adding water is the same for sparging: I get my 4 cup Pyrex cup, dip it in the pot I got at about 175-190, and just pour evenly on the top of the bed. I stir the mash after doing this and tend to stir every 10 minutes during the mash otherwise. From what I understand it's a fairly basic setup and practice.

__________________
Aloha_Brew is offline
 
Reply With Quote Quick reply to this message
Old 01-30-2011, 10:30 PM   #4
MalFet
/bɪər nərd/
HBT_LIFETIMESUPPORTER.png
Feedback Score: 1 reviews
 
MalFet's Avatar
Recipes 
 
Join Date: May 2010
Location: NYC / Kathmandu
Posts: 8,208
Liked 1232 Times on 819 Posts
Likes Given: 561

Default

Quote:
Originally Posted by Aloha_Brew
I got a standard cooler that can hold about 10-12 gallons. I have a small analog thermometer I place in the middle of the mash. To maintain temps for 90 minutes I usually end up adding 1-1 1/2 gallons. My method of adding water is the same for sparging: I get my 4 cup Pyrex cup, dip it in the pot I got at about 175-190, and just pour evenly on the top of the bed. I stir the mash after doing this and tend to stir every 10 minutes during the mash otherwise. From what I understand it's a fairly basic setup and practice.
Hmm...the mash and sparge seem alright. How did the grain crush look? Did you crush it yourself, or order it crushed?
__________________

"Be excellent to each other." -Benjamin Franklin

MalFet is offline
 
Reply With Quote Quick reply to this message
Old 01-31-2011, 02:57 AM   #5
Aloha_Brew
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: Mililani, Hawaii
Posts: 90
Default

Crushed it myself at the brew shop, like I did with all my brews.

__________________
Aloha_Brew is offline
 
Reply With Quote Quick reply to this message
Old 01-31-2011, 10:25 AM   #6
MalFet
/bɪər nərd/
HBT_LIFETIMESUPPORTER.png
Feedback Score: 1 reviews
 
MalFet's Avatar
Recipes 
 
Join Date: May 2010
Location: NYC / Kathmandu
Posts: 8,208
Liked 1232 Times on 819 Posts
Likes Given: 561

Default

Quote:
Originally Posted by Aloha_Brew
Crushed it myself at the brew shop, like I did with all my brews.
Hmm...can't say then. Something was off. If your crush and sparge were just like your last two batches, it must have been something else...temperature, grain weights, a hydrometer reading...

Next time, try taking a hydro reading at various points throughout to see if you can figure out where you're losing/not getting your initial points.
__________________

"Be excellent to each other." -Benjamin Franklin

MalFet is offline
 
Reply With Quote Quick reply to this message
Old 02-01-2011, 04:38 AM   #7
Aloha_Brew
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: Mililani, Hawaii
Posts: 90
Default

Yeah, I'm going to have to. The only big difference between my other two batches is this one was at a higher temp by 3 degrees and I also managed to maintain a constant temp better. The other two fluctuated kind of low. But this is also the first time I used so much Pilsen as the base malt...

Ah well, I'll chalk it up as a partial failure and look forward to the flavor at less "potency" as it were. Thanks for your assistance.

__________________
Aloha_Brew is offline
 
Reply With Quote Quick reply to this message
Old 02-01-2011, 10:51 AM   #8
meadowstream
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2009
Location: Boston, Massachusetts
Posts: 248
Liked 9 Times on 8 Posts
Likes Given: 34

Default

1. Crush (do you use a spark plug gapper or some other device to make sure rollers are the right distance apart?)

2. Temperature - 149 would give you more complete conversion than 152, so this could be part of the issue

3. Volume of water (can't tell what volume you used during mash, but too much could be a problem...but you have had success previously using the same volumes, so probably not a factor.)

4. Hydrometer - any chance that this instrument is miscalibrated?

__________________
meadowstream is offline
 
Reply With Quote Quick reply to this message
Old 02-01-2011, 02:23 PM   #9
Northcalais40
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2010
Location: south of hardwick
Posts: 425
Liked 7 Times on 6 Posts

Default

I'll bet dollars to donuts that you are not getting full conversion in the mash. You need to get Iodaphor and do a conversion test, before you can be sure that your mash is done. My mashes always take 60-90 min before they turn up iodine negative. Then you need to maximize the lautering process. Whether batch sparging or fly sparging, you need to have enough water so that you don't leave a lot of sugar in the spent grain.

__________________
Northcalais40 is offline
 
Reply With Quote Quick reply to this message
Old 02-01-2011, 08:40 PM   #10
Yooper
Ale's What Cures You!
HBT_ADMIN.png
Feedback Score: 0 reviews
 
Yooper's Avatar
Recipes 
 
Join Date: Jun 2006
Location: Upper Michigan
Posts: 61,061
Liked 4471 Times on 3253 Posts
Likes Given: 870

Default

Quote:
Originally Posted by Aloha_Brew View Post
I got a standard cooler that can hold about 10-12 gallons. I have a small analog thermometer I place in the middle of the mash. To maintain temps for 90 minutes I usually end up adding 1-1 1/2 gallons. My method of adding water is the same for sparging: I get my 4 cup Pyrex cup, dip it in the pot I got at about 175-190, and just pour evenly on the top of the bed. I stir the mash after doing this and tend to stir every 10 minutes during the mash otherwise. From what I understand it's a fairly basic setup and practice.
I'm not sure I understand. You have to add 1.5 GALLONS of water to your mash to maintain the temperature? That doesn't make sense.

Here's what I'd suggest. Preheat your cooler, using 1.5 quarts of water per pound of grain, by adding 180 degree strike water to your cooler. Cover it. When it gets down to 165, then add your grain. Stir well, to equalize the temperatures throughout. If the temperature is different in one place than another, stir some more. When you're at your desired mash temp
(153 in my example), cover it and walk away for 60 minutes. Don't add 1.5 gallons of water during the mash! Get it right when you dough in, and don't mess with the mash.

And no more "about 175-190 degrees"! Be precise. Get a better thermometer, and use the correct temperatures for the mash and the sparge. Use the correct amount of water also. This will give you predictable and repeatable results, rather than "about this temperature" which you're finding doesn't really work.
__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006
Yooper is offline
 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools