Specific Gravity way off...

[Russellvdg]

I just brewed an all grain 5.5 gal batch of scotch strong ale. My calculations estimated the specific gravity to hit 1.086 and it turned out to be 1.062 (I measured at 65f). My mash temps were right, and my volumes were close (think I over sparged by 1.4 qts). This makes me think I have to be doing something way wrong in the mash to be this far off. I would like to make this again in a week or two on the same yeast cake, once I can identify my problems and correct them.
I would like to list the recipe and procedure and see if anyone can notice any glaring errors. Besides the lower gravity, the beer has turned out well thus far and i expect a good but weaker result.

10# Pale malt
3# Munich
2# Melanoiden
2# Dextrine
4 0z Special B
4 Oz Smoked

2 oz Goldings 3.7% 75 min boil
Whitelabs Edinburg Ale Yeast (made starter)
1 tsp Irish Moss

Single step mash, target temp 158
Boil time 75 min
Stike water: 21.9 qts @ 171.5
Mash out: 8.75 qts @196.6
Sparge water: 7 qts @ 170 (overshot volume by 1.4 qts)

(Mashing in a picnic cooler that looses almost half a gallon in the false bottom and I check temps with 2nd thermometer)

My Procedure:
-preheat cooler 10 min, dump water
-add strike water and grain, stir till grain is mixed well with no lumps or pockets (2 min), check temp, close the lid, wait an hour
-add mash out water, stir for a minute, wait 15 min for grains to settle, vorloft, drain it completely and add to boil kettle
-add sparge water, stir for a minute, let it settle 10-15 mins, vorloft, drain add to kettle


So there it is. Any help would be much appreciated.

Cheers!

 

[Walker]

To be clear, you measured 1.062 OG on a final volume of 5.5 gallons in your fermenter?

 

[nebben]

The 1.062 measurement was made after you boiled the wort? How much wort did you collect and put into the fermenter?

Your steps are almost identical to mine, except with your mashout step. I routinely see 78% efficiency, or around there, even with that much grain. It would be interesting to see what your 7 quarts of sparge was, gravity-wise.

Other than this, how was your crush? Do you brew with this system and see a ~75% number more often? 54% is pretty close to what I got when I did a first-runnings-only barleywine with 20lbs+ grain.

 

[Walker]

While I wait for an answer to that, I would say that you didn't sparge nearly enough for that amount of grain, so you left a lot of sugar behind in the mash tun.

With 15.5 pounds of grain, I'd be using a (batch) sparge volume of close to 4.5 gallons and would be looking at a pre-boil volume of 8.5 or 9 gallons. That would need a loooooooooong boil to get down to 5.5 gallons even at a hearty boil off rate of 1.5 gallons/hour.

I count mash-out water as part of my sparge water, so it looks to me like you mashed at 1.4 qt/lb (sounds great) but only sparged with a about 1 qt/lb, which is very low, IMO, especially with such a large dead-space in the MLT.

 

[Russellvdg]

Yes, I measured 1.062 in the primary, just after chilling and before pitching the yeast.

Sounds like I should have used more sparge water and that makes sense in hind sight. The last wort that was drained didn't seem much weaker than the initial runoff. So do I just use more sparge water and boil it for a long time or do I accept lower efficiency and throw more grain at it? What do most brewers do for high gravity beers?

Thanks!

 

[Russellvdg]

The 1.062 measurement was made after you boiled the wort? How much wort did you collect and put into the fermenter?

Your steps are almost identical to mine, except with your mashout step. I routinely see 78% efficiency, or around there, even with that much grain. It would be interesting to see what your 7 quarts of sparge was, gravity-wise.

Other than this, how was your crush? Do you brew with this system and see a ~75% number more often? 54% is pretty close to what I got when I did a first-runnings-only barleywine with 20lbs+ grain.

I didn't take a volume measure after the boil but eyeballed it in my primary to be a quart or two higher than normal. Crush looked to be normal.
I've only brewed a hand full all grain beers and haven't really had the tools to calculate efficiency til recently. So it's hard for me to say what I normally see. This is actually my first batch back in 6 months or so and i just found beersmith. I was doing calculations by hand on my first batches. But I would say that they were a lot closer to the mark than this one.

I wish I would have taken a reading on the sparge too.

 

[nebben]

For my high gravity brew session that I did last, I made a barleywine with the first runnings plus some of the 1st sparge. I didn't want to extract a lot of wort that would need to be boiled down for hours and hours. Instead, I made a partigyle and had a lower gravity batch of wort for the latter part of the 2nd runnings and the 3rd runnings. My first 5 gallons after boil finished at roughly 1.098 and the 2nd 5 gallons finished at 1.048.

 

[iron_city_ap]

I just brewed 2 batches the last 2 days and came up short as well. About .01 both times. I'm not quite sure what I did wrong, but it looks like it was something on my end for sure. Anyhow, just wanted to let you know you aren't alone.

 

[Russellvdg]

For my high gravity brew session that I did last, I made a barleywine with the first runnings plus some of the 1st sparge. I didn't want to extract a lot of wort that would need to be boiled down for hours and hours. Instead, I made a partigyle and had a lower gravity batch of wort for the latter part of the 2nd runnings and the 3rd runnings. My first 5 gallons after boil finished at roughly 1.098 and the 2nd 5 gallons finished at 1.048.

Cool that makes sense. So it looks like when brewing an all grain high gravity beer, you are stuck with a single batch of beer with poor efficiency and a normal boil time, a single batch of beer with better efficiency and super long boil time, or two batches of beer.... It would be interesting to see a graph that plotted efficiency (as a percentage),water required, and boil time to reach desired volume. Not sure what that would look like though, but it might help me figure out what to do if I make this again.

I don't think I want to make a double batch of beer, though it might be an option in the future. Maybe I will modify my mash tun to not lose the half gallon that I'm accustomed to, split the wort into multiple kettles to increase the rate of evaporation and sparge with more water. I'll have to crunch some numbers but seems like it might work.

Thanks all!