Trying to figure out what went wrong

A couple months ago I brewed a sweet stout and it was great, the keg only lasted 1 week.. Last month I brewed the same recipe (scaled up to 5.5 from 5.0 gal) and my OG, FG and abv are a bit off. I understand that my IBU will be a bit lower but the other numbers have me confused.

Here's the first run(5 gal);
4.50 lb Amber Dry Extract
1.50 lb Wheat Dry Extract
0.75 lb Caramel/Crystal Malt - 60L
0.75 lb Chocolate Malt (350.0 SRM)
0.50 lb Roasted Barley (300.0 SRM)
0.75 lb Lactose (Boil 10 min)
10 oz Quaker Oats (Boil 10 min)
0.75 oz German Magnum [13.40 %] (60 min)
1.00 Wirfloc Tablet (Boil 10 min)

Steeped grains in 3 gallons @ 154f - 1 hour
Add Amber DME
Bring To Boil
Add German Magnum
Add Wheat DME @ 30 min
Add Wirfloc @ 50 min
Add 10oz Oats @ 50 min
Add 12oz Lactose @ 55
Add water to 5.0 gal

Pitched WLP051 @ 72f - 1liter starter
Fermented @68f for 3 weeks

OG - 1.059
FG - 1.022
ABV - 4.85%

Second run(5.5 gal)
4.95 lb Amber Dry Extract
1.65 lb Wheat Dry Extract
0.83 lb Caramel/Crystal Malt - 60L
0.83 lb Chocolate Malt (350.0 SRM)
0.55 lb Roasted Barley (300.0 SRM)
0.83 lb Lactose (Boil 10 min)
12oz Quaker Oats (Boil 10 min)
0.83oz German Magnum [13.40 %] (60 min)
1.00 Wirfloc Tablet (Boil 10 min)

Steeped grains in 3 gallons @ 154f - 1 hour
Add Amber & Wheat DME
Bring To Boil
Add German Magnum
Add Wirfloc @ 50 min
Add 12oz Oats @ 50 min
Add 14oz Lactose @ 55
Add water to 5.5 gal

Pitched WLP051 @ 73f - No starter
Fermented @68f for 3 weeks

OG - 1.065
FG - 1.020
ABV - 5.9%


The only difference between the two was using a starter on the first batch and a late addition on the wheat dme.. Can these 2 really make that much difference or did I scale the recipe wrong? What am I missing here??

Thanks.

Different temperatures when you took the OG?

MC

72f on the first batch, 73f on the second. Temps & OG were taken just before pitching the yeast.

Zubius said:

A couple months ago I brewed a sweet stout and it was great, the keg only lasted 1 week.. Last month I brewed the same recipe (scaled up to 5.5 from 5.0 gal) and my OG, FG and abv are a bit off. I understand that my IBU will be a bit lower but the other numbers have me confused.

Here's the first run(5 gal);
4.50 lb Amber Dry Extract
1.50 lb Wheat Dry Extract
0.75 lb Caramel/Crystal Malt - 60L
0.75 lb Chocolate Malt (350.0 SRM)
0.50 lb Roasted Barley (300.0 SRM)
0.75 lb Lactose (Boil 10 min)
10 oz Quaker Oats (Boil 10 min)
0.75 oz German Magnum [13.40 %] (60 min)
1.00 Wirfloc Tablet (Boil 10 min)

Steeped grains in 3 gallons @ 154f - 1 hour
Add Amber DME
Bring To Boil
Add German Magnum
Add Wheat DME @ 30 min
Add Wirfloc @ 50 min
Add 10oz Oats @ 50 min
Add 12oz Lactose @ 55
Add water to 5.0 gal

Pitched WLP051 @ 72f - 1liter starter
Fermented @68f for 3 weeks

OG - 1.059
FG - 1.022
ABV - 4.85%

Second run(5.5 gal)
4.95 lb Amber Dry Extract
1.65 lb Wheat Dry Extract
0.83 lb Caramel/Crystal Malt - 60L
0.83 lb Chocolate Malt (350.0 SRM)
0.55 lb Roasted Barley (300.0 SRM)
0.83 lb Lactose (Boil 10 min)
12oz Quaker Oats (Boil 10 min)
0.83oz German Magnum [13.40 %] (60 min)
1.00 Wirfloc Tablet (Boil 10 min)

Steeped grains in 3 gallons @ 154f - 1 hour
Add Amber & Wheat DME
Bring To Boil
Add German Magnum
Add Wirfloc @ 50 min
Add 12oz Oats @ 50 min
Add 14oz Lactose @ 55
Add water to 5.5 gal

Pitched WLP051 @ 73f - No starter
Fermented @68f for 3 weeks

OG - 1.065
FG - 1.020
ABV - 5.9%


The only difference between the two was using a starter on the first batch and a late addition on the wheat dme.. Can these 2 really make that much difference or did I scale the recipe wrong? What am I missing here??

Thanks.

Click to expand...

The red highlighted part is the answer. When you topped off with water you got incomplete mixing of the wort and water so you picked up a sample that had more wort than water and it gives you a (false) higher OG. Don't worry or be ashamed about it, that happens often. If you are mathematically inclined you can figure out from the fermentables what the OG must be. I just ignore it and worry about getting the proper FG.

Thanks RM-MN, I'll keep an eye on that this weekend when I brew this again.