When Gravity Readings Just Don't Make Sense / Can I blend?

General Homebrew Discussion
1

Brewed the following IPA-borderline-IIPA this past weekend.  I have been brewing in a bag and typically getting around 75% efficiency.  This time I did a superfine double crush through the mill, 75-minute mash (as usual for BIAB) with mash hops, and a single batch sparge in a spare fermenter with 170* water.  The only difference is I didn’t do a 10minute mash out.

I am dumbfounded because after my ‘lauter’, I had 7.5 gallons of wort @ 1.047 pre-boil.  Based on the 90 minute boil I was doing, I figured I would be down to at least 6 gallons as my blichmann burner evaporates like a mofo.  So:

7.5 gallons @ 1.047 = 352 gravity points
6.0 gallons end volume = 1.058 OG PLUS 1# cane sugar, which should have added about 8-9 gravity points.  1.067-68, not the end of the world.

First off, my efficiency was miserable this time (total grist of 14.75# = 545 possible gravity points, 352/545 = 64% efficiency or ugh.  Have NO IDEA why it was so bad.

Anyway, here is the weirdest part.  I decanted the wort after chilling off the trub, aerated like crazy, and took a small refractometer sample.  15 brix, or about 1.060.  WTF?  Since this was bordering on a IIPA, and most of my hops were late, I went a little nuts with hop additions, bittering to 105.8 calcuated IBUs thinking that a BU:GU ratio of 1.38 was a touch high, but wouldn’t TASTE that bitter, as most were late.  Then, when I had this abysmal gravity of 1.060, my BU:GU ratio became more like 1.76.  Ouch.  And bitter.

I gave this a taste tonight, and it was pretty damned bitter (not terrible but bitter, even for my tastes).  It is super early (pitched 2 packs of US-05 Sunday night @ 10pm), as I was adding 3oz of dry hops per Tasty’s method of tail end of fermentation, so maybe its not done fermenting…

Any thoughts on what could have happened with my gravity?  It makes no sense at all.  Also, could I brew and ferment one gallon of malty, high-gravity beer and blend?

Flight of the Phoenix IIPA
14-C Imperial IPA

Size: 5.5 gal @ 68 °F
Efficiency: 75.0%
Attenuation: 81.6%
Calories: 251.62 kcal per 12.0 fl oz

Original Gravity: 1.076 (1.075 - 1.090)
Terminal Gravity: 1.014 (1.010 - 1.020)
Color: 12.33 (8.0 - 15.0)
Alcohol: 8.17% (7.5% - 10.0%)
Bitterness: 105.8 (60.0 - 120.0)

Ingredients:
0.5 ea Campden Tablet - added during boil
12.75 lb (81.0%) American 2-row - added during mash
.5 lb (3.2%) Crystal Malt 20°L - added during mash
.5 lb (3.2%) Crystal 40 - added during mash
1 lb (6.3%) Melanoidin Malt - added during mash
1 lb (6.3%) White Table Sugar (Sucrose) - added during boil
1 oz (8.3%) Caliente (17.8%) - added during mash
1 oz (8.3%) Columbus (15.0%) - added first wort
.75 oz (6.2%) Magnum (14.5%) - added during boil, boiled 60 m
.3 oz (2.5%) Amarillo® (8.5%) - added during boil, boiled 20 m
.3 oz (2.5%) Centennial (10.0%) - added during boil, boiled 20.0 m
.3 oz (2.5%) Caliente (17.8%) - added during boil, boiled 20.0 m
.3 oz (2.5%) Amarillo® (8.5%) - added during boil, boiled 15.0 m
.3 oz (2.5%) Centennial (10.0%) - added during boil, boiled 15.0 m
.3 oz (2.5%) Caliente (17.8%) - added during boil, boiled 15.0 m
.5 oz (4.1%) Centennial (10.0%) - added during boil, boiled 10.0 m
.5 oz (4.1%) Caliente (17.8%) - added during boil, boiled 10.0 m
.5 oz (4.1%) Centennial (10.0%) - added during boil, boiled 5.0 m
.5 oz (4.1%) Cascade (5.5%) - added during boil, boiled 5.0 m
.5 oz (4.1%) Caliente (17.8%) - added during boil, boiled 5.0 m
.5 oz (4.1%) Centennial (10.0%) - added during boil
.5 oz (4.1%) Cascade (5.5%) - added during boil
.5 oz (4.1%) Caliente (17.8%) - added during boil
.5 oz (4.1%) Amarillo® (8.5%) - added during boil
1 oz (8.3%) Cascade (5.5%) - added dry to secondary fermenter
.5 oz (4.1%) Centennial (10.0%) - added dry to secondary fermenter
.5 oz (4.1%) Caliente (17.8%) - added dry to secondary fermenter
1 oz (8.3%) Amarillo® (8.5%) - added dry to secondary fermenter

00:03:00 Dough in - Liquor: 6.0 gal; Strike: 162.79 °F; Target: 153 °F

2

Yes you can brew a high gravity beer and blend gently. It may be tricky to get what you intend though, so if the beer tastes good I’d recommend sticking with it and learning for the next batch.
Is the OG of this batch much higher than ones that you’ve been able to get better efficiency from? It is fairly normal to get lower efficiency with larger grain bills.

3

A ‘touch’ bigger in OG I suppose.  Maybe 10-20 points at most?

In any event, I tried this beer last night, after 10 days primary or so and 5-6 days of dry-hopping.  Going to leave the dry hops for a bit longer, but the beer is MUCH better already.

I suppose I need to just use patience to blend with my beer :wink:

4

Its not unusual to lose a good 5% in efficiency when brewing a bigger beer.  Its just a matter of the larger portion of bound water in the grain keeping more of the sugars behind.  Next time you can just add 5% more grain to compensate, or sparge a little more and boil longer.

5

Are you checking your conversion efficiency? It could be that you aren’t getting full conversion without the mash out.

Did you take the pre-boil reading before or after the boil started? It could just be stratification.

How are you taking the readings? Hydrometer or refractometer? Do you chill the sample in a sealed container? Have the instruments been calibrated recently?

15°Bx is ~1.061 SG, and your post-boil reading with the sugar should be ~1.066, so you aren’t that far off.