Extremely low efficiency...why?

[snowveil]

I decided to use some extra ingredients to brew an IIPA today. I figured I'd do a 3gal batch since my primary is filled with something else right now and I can use some food-grade buckets I got from the grocery store bakery.

The grain bill was as follows: (for 3 gallons)
9lb 2-row pale
1lb flaked rye
8oz crystal 40

Brewtarget estimated 1.105 at 65% efficiency (modest, I figured) with a preboil gravity of 1.073

I mashed with 4 Gallons at 151*F for 1 hour, then collected the first runnings, then sparged with 1.5 Gallons at 168*F to get to my preboil volume of 3.5 Gallons.

My preboil gravity was only 1.060! If I'm using Brewtarget correctly, this puts me at only 54% efficiency.

What could have gone wrong? I haven't had GREAT efficiency in the past, (mid sixties or higher) but this seems pretty out of whack.

The only thing that I can think of that I changed (outside of planning a 3 gal batch instead of 5 gal) is that I used tap water instead of a 50/50 mixture of tap and RO. Could this account for this poor of an efficiency?

 

[ajf]

Have you made any other high gravity AG beers before? As you have a large grain bill, and are using very little water for sparging, I would expect your efficiency to drop considerably. If you have the right equipment, and fly sparge very slowly, you may be able to get your efficiency up a bit, but sparging 10 1/2 lb grain with 1 1/2g water. You could also try mashing a bit thicker next time, say 1.25 qt / lb, which would leave you a bit more water for sparging.

-a.

 

[snowveil]

I calculated it out to mash with appx 1.5qts/lb so the sparge volume was pretty limited. I have heard that a higher mash volume than 1.25qts/lb is not detrimental to conversion so I figured I'd go higher than 1.25 by just a bit.

This is my first high gravity AG batch....the highest I've done was about 1.071, this one wound up being at 1081 after the boil. The 1071 I missed by a few points, but 30 points seems excessive...

Fly sparging isn't really something I'm looking into right now as I'm still pretty new to AG as it is and don't want to complicate things with a new setup just yet.

 

[snowveil]

sorry, just read that you said mash *thicker* (not thinner) next time....why would this be helpful? I'd have figured that a thinner mash would allow for more area for the converted sugars to come out....is a thinner mash and larger sparge better than a thin mash and small sparge?

 

[Got Trub?]

sorry, just read that you said mash *thicker* (not thinner) next time....why would this be helpful? I'd have figured that a thinner mash would allow for more area for the converted sugars to come out....is a thinner mash and larger sparge better than a thin mash and small sparge?

You meant thicker right? Because it allows you to use a larger volume of sparge water. When I do big beers I also see a significant drop off in efficiency. One way to compensate is to use a larger starting volume at the beginning of the boil and boil for 2 hours instead of 1. That also allows you to use more sparging water.

GT

 

[ksbrain]

I seem to get better efficiency from a thinner mash, too. I think the big beer low efficiency thing is because you don't draw off relatively as much wort from the grain as you would for a smaller beer. So you leave a lot behind, or your last runnings have a higher gravity than the last runnings from a smaller beer.

If you mash ten pounds of grain for seven gallons, when you mash fifteen pounds of grain it's logical to think you'd need ten gallons of wort to expect the same efficiency.

 

[wonderbread23]

Next time use more sparge water... I like to use 1.5-2X my strike volume. If you end up collecting too much runnings, just increase your boil time. Also, for big beers I have no problem mashing at 1qt/lb.

 

[TotemWolf]

How did you figure your gravity for the recipe? With that grain bill at 65% eff I only come up with the OG of 80.

[(36 x 9)/3] + [(32 x 1)/3] + [(34 x 0.5)/3] x 0.65 = 80

 

[malkore]

I too would say lower the mash volume (say 1.2qt per pound) so you have more sparge water to rinse the sugars. the mash volume activiates enzymes and removes some sugar, but the sparge is really the 'rinse' phase.

sorta like a washing machine. that first spin cycle throws a lot of the soap out of the cloths, but you still need a rinse cycle (or two) to get them fully rinsed.

I often do a double batch sparge and I do see an efficiency increase by a few %.

 

[TotemWolf]

It does matter what your water to grain ratio is if to start with there is not enough gravity point in the grain bill. With 100% eff you could only get an OG of 1.124 with the grain bill.
In order to get an OG of 1.105 with that grain bill, you would have to have an eff of 98%. With 65% you are only, ever, no matter what, going to get 1.080 OG. You mash was good. It was your math that was bad.

 

[snowveil]

It does matter what your water to grain ratio is if to start with there is not enough gravity point in the grain bill. With 100% eff you could only get an OG of 1.124 with the grain bill.
In order to get an OG of 1.105 with that grain bill, you would have to have an eff of 98%. With 65% you are only, ever, no matter what, going to get 1.080 OG. You mash was good. It was your math that was bad.

I didn't even try to simplify it out that way. I basically just put the ingredients into brewtarget and figured it was caculating things fine...I don't know how it got the stuff that far off but I'm glad that my process wasn't cancerous (maybe just a bit of a head cold...gotta try to get above 70% ).

I'll definitely double-check program calculations next time before brewing or ordering ingredients

 

[joex444]

Not sure how you got those values, but indeed that grain bill for 3 gallons gives OG 1.105 at an efficiency of 83%. At 65%, you're at 1.082.

And yes it is better to mash thick and have a large sparge volume. For high gravity batches, I'll mash in at 1qt/lb. Everything else gets 1.25qt/lb. There's no harm in doing more -- but there's no benefit either. You do get a benefit by sparging more so why not use that extra strike water as sparge water and get a bit more out of the grains?