Extract OG issues are befuddling me

I just loaded my 3rd batch into the fermenter last night and for the second time in a row I was about 10 points under projected OG. I have converted any reading for temperature difference and followed the recipes very closely.

They have both been extract plus specialty grains recipes.

I employ a steep small(mid 150's for 30-60 min depending on recipe) then add water for a full boil. I do a small initial extract addition(1/4) and the rest 10-15 minutes before flame out.


Last nights batch required no water topping off, the batch one prior did require less than a gallon.


If I weigh my ingredients and follow my recipes exactly(with the exception of late additions and steep small in some cases) how can I have so much variance from the projected OG? Yes, I tested my hydrometer this morning....

In cases where you top off getting an accurate reading is pretty hard. Mixing the top off water with the wort completely is nearly impossible, but rapid fermentation takes care of that for you. Skewed readings in this case are frequent.

10 pts seems a bit much, but was last night's batch over the 5 gallon mark? Are you checking gravity before or after pitching the yeast? I would assume before, but you never know.

What type of extract are you using? Getting every last drop of LME out of the container takes patients.

Last night I used all dme, and I'm taking my readings pre yeast. The batch was 6 gallons, to account for true loss, slightly over 5 ended up in the fermenter. Could it be that I'm not getting enough of the grain converted to sugar?

I tie a knot in my grain bag, does that not allow for the grain to expand and lead to decreased efficiency?

Xpertskir said:

I just loaded my 3rd batch into the fermenter last night and for the second time in a row I was about 10 points under projected OG. I have converted any reading for temperature difference and followed the recipes very closely.

They have both been extract plus specialty grains recipes.

I employ a steep small(mid 150's for 30-60 min depending on recipe) then add water for a full boil. I do a small initial extract addition(1/4) and the rest 10-15 minutes before flame out.


Last nights batch required no water topping off, the batch one prior did require less than a gallon.


If I weigh my ingredients and follow my recipes exactly(with the exception of late additions and steep small in some cases) how can I have so much variance from the projected OG? Yes, I tested my hydrometer this morning....

Click to expand...

Calibrate the bucket you are using to bring your work up to its final volume.

My bucket's printed gallon markings are way off. At 5 gallons, it's off by at least a half gallon. Using several measurement devices, fill your bucket to gallon or half gallon increments and mark it with permanent marker. Use these marks going forward.

I used a couple of measuring cups and pre-marked buckets for calibration. I even used the precise fill on my refrigerator to make sure the measuring devices were accurate. All were almost exactly the same but all were way different from the marks on the bucket. This tells me the bucket's markings were way off.

I missed my OG an FG with my first two batches. I had filled about 59 bottles instead of 53 so I knew something was wrong. After calibrating my bucket, my OG and FG were almost exactly what they were supposed to be every time with extract brews.

I would agree on checking your markings. When you say just over 5 gallons went into the fermenter, that makes it a 5 gallon batch. 6 gallons may be your preboil volume, but the batch size is 5 gallons.

When brewing extract, especially kits, very rarely is the stated statistics off. If you use the ingredients as directed it becomes a matter of calibration or volume. When using "steeping grains" if they are specialty grains such as crystal40 the starches are already converted. They add color and flavor more so than gravity. If you are steeping base grains such as 2 row that now needs to be a mash. When mashing volume, temp, and time are key to efficiency as you are relying on the mash to add gravity.

I'm curious as to what you have brewed in the batches in question here. Kits or recipies? What is the grain bill?

Batch 1 and 2 were kits. Batch 2 of issue could have been a topping off issue. Batch 3 was a recipe, skeeters zombie dust clone. And it is a 6 gallon batch. I use better bottles and calibrated the markings with a gallon jug myself. I'm brewing today, we shall see what happens. The good news is my first batch tastes way better than I thought it could, and I've had excellent fermentation activity with my 2 other batches, lots of blow off and agressive bubbling.

Calculating your OG with extract it is pretty straightforward. DME should yield around 40-43 points per pound per gallon. If you use 6 lbs of DME in a 5 gallon batch (postboil volume) your OG should be in the neighborhood of 1.050
Using this formula you'll at least know if the gravity you expect is reachable.
As for the steeping grains, the contribution to OG is probably minimal, maybe a couple of points

How to Brew has a good section on this http://www.howtobrew.com/section1/chapter3-4.html

Ok, Mysteries solved apparently. His recipe is off, he says of of 1.065 for a 6 gallon batch with 6lbs dme with 2.5lbs of grains. So apparently I hit the numbers fine at 1.054. I'll attribute the other issue to topping off. Full steam ahead, I'll nail my OG when I brew later.