miss OG by a lot

[avm221]

i brewed a russian imperial stout today and the OG that my computer gave me was 1.124 and i got 1.090. that is a huge difference, this is new equipment and im still getting used to it but that just still a lot, anything i can do to make it better?

 

[BlindFaith]

There would be a lot more information needed to help: grain bill, volumes used, mash temp, water type used, AG or PM, etc..........

 

[avm221]

It was a all grain batch, 22lbs of grain 14lbsMO the rest specialty grains. Mashed at 152 in a cooler for an hour batch sparked at 160 o dos a 90min boil.

 

[duboman]

Could be pH or quality of crush as well. In addition my experience with really large grain bills is efficiency decreases a bit due to the sheer volume in the mash tun. Did you stir a few times during the mash? It can help.

My efficiency is always 82% but with more than 18# of grain I get more like 75% so I adjust for that decrease with my recipes, you might need to do the same.

 

[avm221]

Yes I did stir 4 times during a 60min mash

 

[avm221]

Im just disappointed it will be an imperial stout at only 7% I was hoping for closer to 10%. So how can I get better number with big grain bills?

 

[lumpher]

main thing you need to consider is the bigger the beer, the worse efficiency you get. on a beer that big, i plan for 65%. i get close to 80 on a normal 5-6%

 

[BlindFaith]

Im just disappointed it will be an imperial stout at only 7% I was hoping for closer to 10%. So how can I get better number with big grain bills?

Is your water hard or soft? What water ratio are you using (1.25 qts per lb, 1.35, 1.5)? Are you mashing out? Batch Sparging, Fly Sparging? Have you always had low OG or just on this bigger beer? I had a water problem where I was getting bad efficiency on lighter beers and decent on dark. I went to baseline RO water with additions from this wonderful thread: https://www.homebrewtalk.com/f128/brewing-water-chemistry-primer-198460/

It could be your crush, pH, process, thermometer, or water. You'll just have to troubleshoot, but until you get your numbers right you can always add some DME at flameout to get your OG correct.

 

[acidrain]

batch sparked at 160 o dos a 90min boil.

Got some typos there... does that mean you were supposed to boil for 90 min? I saw in your other reply that you only boiled for 60 min. What is your boil-off rate?

 

[avm221]

Sorry been doing this on my phone..
60min mash at 150
sparge at 160
90min boil

 

[woknblues]

Sorry been doing this on my phone..
60min mash at 150
sparge at 160
90min boil

You might end up ok if you mashed on the lower side and your beer dries out a bit more than expected. A smooth eight percenter will also finish quicker than a ten percenter, so i bet that you will be enjoying that ris THIS cold season instead of the NEXT one!

 

[duboman]

As mentioned you can add DME at flame out or you can up the grain bill to account for the decrease in efficiency.

One pound of DME will raise your gravity .009 in a 5 gallon batch.

 

[avm221]

i think we have hard water. i used the ratio 1lb to 1.5qt for the mash
here is the recipe that i used:

Russian Imperial stout
5 gal batch
brewed: 5/31/13
OG: 1.090

14 lbs Maris Otter Malt
3 lbs Munich Malt
1 lbs Crystal 80
1 lbs CaraMunich Malt
1 lbs Chocolate Malt
1 lbs Special Roast Malt
.75 lbs Special B Malt
1.2 lbs Roasted Barley
.75 lb Brown Malt

.75 lbs corn sugar (boil 90 minutes)
Hops
1 oz Northern Brewer (9.0% alpha acid) 60 minutes
1 oz Challenger (7.5% alpha acid) 60 minutes
.5 oz Target (10.0% alpha acid) (20 minutes)
Yeast
1Pack Wyeast 1728 Scottish Ale yeast

 

[avm221]

i have used filtered water before i just did that because i didn't like the taste of the water that was coming out of the tap, but dose this chemically change my mash? but this last batch i used 5 gals of filtered and then tap water too.

 

[pdxal]

Get ready for a high FG on that beer too, based on that grain bill.
Also, you might mash out/sparge hotter.

 

[avm221]

What temp would.you suggest for the sparge?

I punched in the numbers if the yeast does it's job it will only get to 8abv

 

[duboman]

What temp would.you suggest for the sparge?

I punched in the numbers if the yeast does it's job it will only get to 8abv

168-170 is an ideal sparge temperature.