What happened! Missed OG by .02

[instinct2]

I'm usually within a few points of my OG, but was way off today. This was the largest grain bill I've ever used. Tried to make a 9.21% imperial stout (7 gallons).

Recipe was based off a yeti clone, matched to my system on beersmith 2.0

Grains
21lbs - Briess pale 2row
1/2lb - Carmel crystal 120
1/2lb - black malt
1/2lb - chocolate malt
3/4lb - roasted barley
3/4lb - rye flaked
3/4lb - wheat flaked

Mash water was 7.25 gallons (should have been 7.75 gallons - only mess up I found)
Mashed in at 169 and mashed 1hour at 150-52 running Hermes coil most of the hour.
First running gravity was 1.074 (this was to be my boil gravity!!)
I sparged with 168 water for my preboil 8.5 gallon. I was at 1.057ish preboil. My OG finished at 1.070 at yeast entry. I know I could have added dme, but I was fine with the gravity of where it's at, but very confused with what I did wrong today. Thoughts? Any other information needed?






Sent from my iPhone using Home Brew

 

[estricklin]

I dunno what method you used but when I do big beers, and I admit I don't do them very often, I find that I have to sparge really slow to get close to my desired gravity. Other than that I don't have a clue.

 

[bzwyatt]

Efficiency often decreases with a higher gravity mash.

Have you tried a beer this big before?

 

[BigPerm]

Unfortunately, it can really be a number of things. Efficiency suffers in HG beers. In my experience, it's usually that I didn't get enough of the first runnings drained before I added my first sparge (I'm a batch sparger). Since the SG of your first runnings was low, it sounds to me like a poor grind. Did you see whole malt kernels in there?

I doubt your low mash volume was the culprit, unless your mash looked dry. 1 qt/lb is the low side and you're about a gallon above that. Did you do a starch conversion test?

Sorry for your luck, but it happens sometimes. I brewed a RIS recently with a target OG of 1.100 and ended up at 1.085. Sucks...

 

[instinct2]

Efficiency often decreases with higher gravity beers.

Have you tried a beer this big before?

No this was first time I've ever tried a beer over 7%. But, this seems really off....

 

[bzwyatt]

I don't know exactly why but efficiency decreases with bigger grain bills.

When I mash with 12 lbs I get 75%. 15lbs I get 70%. Equipment and process make a difference but it is common for efficiency to decrease with more grain.

 

[Braufessor]

No this was first time I've ever tried a beer over 7%. But, this seems really off....

The second I attempt a beer over about 1.070 my efficiency plummets. I now just keep some DME on hand to add if I need to make up gravity points on a higher gravity beer.

 

[instinct2]

Unfortunately, it can really be a number of things. Efficiency suffers in HG beers. In my experience, it's usually that I didn't get enough of the first runnings drained before I added my first sparge (I'm a batch sparger). Since the SG of your first runnings was low, it sounds to me like a poor grind. Did you see whole malt kernels in there?

My lbs told me that he milled pretty fine, because he was afraid that I might get my hermes stuck, but my efficiency should be sky high with his milling, lol!! I know exactly what your saying with not letting first runnings completely drain... I didn't do well with that.

 

[instinct2]

The second I attempt a beer over about 1.070 my efficiency plummets. I now just keep some DME on hand to add if I need to make up gravity points on a higher gravity beer.

Do you just factor the dme off your pre-boil gravity and dumb in before boil?

 

[instinct2]

Did you do a starch conversion ?

No I didn't do this. Actually I've never seen this done.... Is it common practice?

 

[BigPerm]

I've never used a herms, but that doesn't make sense to me. Wouldn't sticking a mash with too fine of a grind run you the risk of stopping your herms altogther?

Anyway, with regards to efficiency, it really should have been higher with a finer grist. The real problem is that with so much sugar in solution, a lot will get trapped up dissolved in the water that gets retained in the malt. You can get the most out by sparging to a higher volume than normal, and boiling longer to concentrate it down. I'll bet the gravity of your final runnings was still in the 30s, so you probably left a lot of sugar behind.

 

[Braufessor]

Do you just factor the dme off your pre-boil gravity and dumb in before boil?

Yeah - I will just take a gravity reading with my preboil wort and then see where I am at and add what I need to bring it up. Usually a pound or a bit more is all I need. I also just plan for crappy efficiency.... and add a couple pounds of base malt above and beyond. I just plug in 65-70% or something like that. (I generally get 80-85%+ on a "normal" beer).

 

[BigPerm]

No I didn't do this. Actually I've never seen this done.... Is it common practice?

Absolutely. Get a bottle of tincture of iodine from your local drugstore. When you get ready to sparge, take a small sample (liquid only) and add one drop of iodine. If it stays brown, sparge. If it changes color to black, it's reacting with starch that's still present and you need to mash longer. And, for the love of god, DONT add that sample back to the mash (dont drink it either). With highly modified malts and temps in the 150s, you'll usually have no problems, but more data is always better.

 

[bzwyatt]

Yeah, you basically need to do more rinsing to get more sugars.

 

[instinct2]

I didn't word the lbs comment right. He milled the grains and then found out I was using hermes, so he was afraid that I might get stuck with the grains being milled so fine. Didn't have any trouble though.

 

[estricklin]

Absolutely. Get a bottle of tincture of iodine from your local drugstore. When you get ready to sparge, take a small sample (liquid only) and add one drop of iodine. If it stays brown, sparge. If it changes color to black, it's reacting with starch that's still present and you need to mash longer. And, for the love of god, DONT add that sample back to the mash (dont drink it either). With highly modified malts and temps in the 150s, you'll usually have no problems, but more data is always better.

The iodine test is a nice quick way to check on the progress of conversion, but keep in mind that conversion and extraction are different things. To the best of my knowledge, whether the starches get converted or not isn't related to mash efficiency. In other words, you could theoretically have a runoff full of starches that still has a high gravity, because those unfermentable starches still count as part of your gravity reading.

For a grain bill as mentioned above, I would be thinking that my sparge should last at least 1.5 hours, normally I'm in the 45 min range but with big beers I know I better "slow my roll" or I get a terrible SG. It takes time as the water goes in to pick up all those sugars/starches. If your fly sparging does your false bottom perform well. What type is it? How long was your sparge? Was your grain bed temp close to 170 the entire sparge? I just guessed above that you used a good system because you have a HERMS system. So ruling that out is why I mentioned about the speed of your sparge.

 

[instinct2]

For a grain bill as mentioned above, I would be thinking that my sparge should last at least 1.5 hours, normally I'm in the 45 min range but with big beers I know I better "slow my roll" or I get a terrible SG. It takes time as the water goes in to pick up all those sugars/starches. If your fly sparging does your false bottom perform well. What type is it? How long was your sparge? Was your grain bed temp close to 170 the entire sparge? I just guessed above that you used a good system because you have a HERMS system. So ruling that out is why I mentioned about the speed of your sparge.

System is nice, but this was only my fifth brew on it. My sparge was obviously way to fast, but I have trouble slowing my pumps down. It took maybe 10 min. I drained filled up and drained again... That was basically it.

 

[BigPerm]

The iodine test is a nice quick way to check on the progress of conversion, but keep in mind that conversion and extraction are different things. To the best of my knowledge, whether the starches get converted or not isn't related to mash efficiency. In other words, you could theoretically have a runoff full of starches that still has a high gravity, because those unfermentable starches still count as part of your gravity reading

That's true. However, long-chain carbohydrates may have (slightly) lower solubility so you may see a reduction in apparent efficiency, albeit a small one.

I don't fly sparge anymore, so I don't measure my sparges in terms of time. If your first runnings are where they should be, and you hit your pre-boil gravities, you stop. If the runnings are still yielding appreciable sugar (eg higher gravity than 1.015) and you aren't yet at pre-boil gravity, keep sparging and boil longer (or add DME or accept lower OG).

 

[estricklin]

System is nice, but this was only my fifth brew on it. My sparge was obviously way to fast, but I have trouble slowing my pumps down. It took maybe 10 min. I drained filled up and drained again... That was basically it.

View attachment 214006

Oh my that is niiiiiiiiiiiiiice! I'm building myself a 20 gallon all electric at the moment so until then I'm still using my round cooler setup.

The good news is next time you'll know. Does your discharge on your pump have a valve, I mean is there a valve that you can cut back the flow rate of the pump with?

 

[instinct2]

Oh my that is niiiiiiiiiiiiiice! I'm building myself a 20 gallon all electric at the moment so until then I'm still using my round cooler setup.



The good news is next time you'll know. Does your discharge on your pump have a valve, I mean is there a valve that you can cut back the flow rate of the pump with?

I don't, thinking I need to add a valve on the fly sparge connector.... Just haven't got around to ordering yet. But that's the plan, seen other guys putting on there.

 

[BrewerBrad82]

If your first runnings were 1.074, then I would say you got pretty good efficiency. Based on a 1.5 qt/lb ratio of water to grain, you hit right around 75% (or so) mash efficiency. Since you had over 7 gallons of water in your mash tun, the problem with your preboil gravity is certainly linked to the sparge. If the sparge was very quick it is quite possible that there was a channeling issue where sparge water was just getting right through the mash and out of the tun, while the very sugary wort was still trapped in the grains. With a mash that big you should be able to hit 1.070 (+/- a point or two) using a very slow fly sparge. It is true that efficiency can suffer on large mashes, but with a really slow fly sparge you can make up for some of that. During the sparge it also helps to use a spoon or something similar to carefully cut shallow slits into the top of the grain bed. This can help to even out the water flow through the mash and get out all those sweet, sweet sugars. If you do slit the mash to encourage even sparges just be sure to not disturb the bottom 6 inches or so of the grain bed.