First AG extremely low efficency

Hi There,

Over the weekend I did my first all grain brew. While that's exciting and all, I got really really low efficency (about 60%) . My OG was 1.044 while my target was 1.054.

So while I think it'll still taste good, I have an unintentioned light beer.

Since I had 7.5# of Pilsner malt and 2# of munich malt in my mash, I did a two step infusion mash with a protein rest of 30 min at 122 degrees. Then the saccrification rest was 30 min at 152. I then batch sparged with 168 degree water to a boil volume of 6 gallons and a pre-boil gravity of 1.038.

That said, I didn't do any pH testing of the mash water to make sure it was low enough. I just used tap water.

Any help in figuring out what was wrong would be greatly appreciated. I'd like to do a bit better in the efficency department next time around. Thanks.

Oh, one other thing I remembered. During the protein rest, my probe thermometer leveled at 122 until I stired it at about 15 min and then the level rose to 125, so i'm wondering if there were hotspots in the mash tun. Could that contribute to such a poor efficency?

I doubt the extra 3 degrees did anything to the protein rest, since some say you can go as high as 130 for protein rest. Also I dont think protein breakdown affects the specific gravity much, if at all. Did you do an Iodine test for conversion? Did you batch sparge or fly sparge? Did you recheck your water volume calculations?

You will probably want to do some searches on efficiency, but the first thing that I noticed was your sacc rest was pretty short. Maybe an hour or even 90 minutes might help. Also, did you adjust your hydrometer for the temperature?

You should have sparged more than you did. Another 1- 1 1/2 gallons. I always do two sparges and end up with 7-7 1/2 gallons. Regardless of how you sparge, an AG batch has more volume to start than an extract one and takes longer to boil down.

I agree with the above:
1) Short saccharification rest. While 30m may in fact be plenty long enough for conversion, sometimes it's not. Also, depends on what Pilsner malt you were using...Briess' is not as well modified as others and will take longer to convert in most cases.
2) Didn't collect enough boil volume and left sugar in the tun.

One other thing. If you batch sparge a 152 degree mash with 168 degree water, you actual sparge temperature will be somewhere between 152 and 168. If you add 1 to 1.5g of near boiling water to the mash to start with in order to raise the temp to 168 before starting the sparge (mash out), then you will considerably increase your efficiency. In my case, I improved efficiency by about 10%.

-a.

Thats ****ing brilliant, i never thought about the fact my temp was probably low when adding to the lower temp water. Not even my books covered that. Its true, first hand knowledge is the best.

Thanks for the responses. I did not do an iodine test for full conversion. I will do that next time and give a longer sacc rest next time.

I'm a bit confused about how adding more sparge water would help. If my batch sparge runnings are low, won't adding another gallon or two of water to the sparge only drive down my SG down even lower? If I'm adding more low SG water to my boil, I'd think that would make the aggregate SG of the boil even lower.

So how long do you other AG'ers give your boils? 90 minutes? I went from a little over 6 gallons down to 5 gallons in my one hour boil.

Thanks again.

david_42 and B von B have it right. More rest time and more sparge. You'll end up somewhere closer to 7 gallons, more for a larger brew. Just boil for 90 min instead of 60. You don't need to change the hops, just start the hop clock after you have boiled the wort for 30 minutes.

Don't forget to Stir, Stir, Stir, and then Stir some more! Batch sparging requires a lot of stiring to get the sugar in suspension before you vorlauf. Mashout isn't critical with batch sparging as you will be boiling the wort within minutes of the sparge, however it doesn't hurt to get your sparge temp as close to 168 as you can as the higher temps help rinse the sugars out of the grain bed.

mezman said:

I'm a bit confused about how adding more sparge water would help. If my batch sparge runnings are low, won't adding another gallon or two of water to the sparge only drive down my SG down even lower? If I'm adding more low SG water to my boil, I'd think that would make the aggregate SG of the boil even lower.

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Adding more water to your sparge helps you rinse all of the sugars into solution before you drain the tun, which is the crux of batch sparging and how it differs from fly sparging (where you slowly rinse the sugar off of the grains).

Get plenty of water in the tun for both batches (3.5-4.0 gallons for a "normal" gravity batch) and stir it really well as Waldo says, then let it sit 10-15 minutes before draining the tun.

BTW, I have no problem boiling 7 gallons down to 5.25 (gals or less) in a good, vigorous 60 minute boil.

Sparging more will drive your SG down, but this will be offset in the calculations by the fact that you have collected a greater volume. Efficiency is really how much sugar is in the kettle which is related to the SG and the volume collected.

Question: Fly sparging. You still have liquid fully covering the grainbed while fly sparging, right? (Havn't done any AG brews, just trying to visualize... Man I can't wait to get a AG system...)

Grim, I believe so. As I understand it, the idea is to match the flow rates so that you have the same amount of water going in as coming out so that the water covers the grain bed. I batch sparge though, so if a fly sparger could chime in, please do.

ajf pointed out what I first noticed already. For batch sparging, you want hot hot water in there to get the temps up. My efficiency went from around 70% to up around 75% by making sure I was getting the whole grain bed up around 170F during mashout and sparging.