In the fall of 2011 I made the leap from extract/partial kits to all-grain kits. I'm enjoying AG, but my SG is continuously below the expected. I have brewed 5 AG kits and 4 have had a low SG.

My assumption is my sugar extraction during mashing (or sparging) isn't optimal. I heat my mash water to 165 and mash the grains for 60 minutes. Mashing levels out at 152. For Lautering I heat the water to 175-180. After I drain the initial mash I add the lautering water and let that soak for 10 minutes. the temperature levels out around 170-172. Then I drain into the kettle and being the boil.

I aim for a gentle boil just enough to break the surface tension. I boil for 60 minutes, chill, rack, take a reading and pitch yeast.

Here are some of the numbers

type            expected     actual  kit
st paul porter  1.052        1.039   http://www.northernbrewer.com/shop/st-paul-porter-all-grain-kit.html
belgium strong  1.067        1.055   http://www.midwestsupplies.com/superior-strong-ale-all-grain-kit.html
troegs hop back 1.063        1.049   http://www.byo.com/stories/recipeindex/article/recipes/90-american-amber-a-pale-ale/2196-troeegs-hopback-amber-ale-clone

The fuorth was the Phat Tyre kit from Northern Brewer. Can't remember the SG though. It was low. They taste great, but the numbers weren't "right". What can I adjust so the numbers are more inline with the recipe?

Update Thank you for all the feedback. There are a number of factors for me to review and adjust. Given my current setup I will follow @mdma advice and recirculate the wort once and extend lautering to 30 minutes.

It will be a week or two before I can attempt this, so it will be awhile before I report back again.

Update #2 I now have some awesome local contacts who are helping me out with technique and trouble shooting. Another (major) issue I could be experiencing is draining the wort way too fast. According to my friend. The drain should be low and slow after cycling a gallon or 2 of wort. sparging should take ~2 hours. for each gallon drained plato/brix should drop 3 points and go no lower than 3-5 points at the end.

the second recommendation is to heat up 3-5 gallons of water to 180 and poor it in prior to/while sparging.

my first attempt using this technique proved successful with the gravity being a lot closer to the anticipated OG. I had some temp issues with the batch, but I was so focused on sparging that I ignored the temp. My guess is I would have been right on if my temp didn't fall so low.

Update #3 I had the chance to brew with my mentor this weekend and he pointed out 2 glaring problems with my mashing technique.

  1. Starting mash temp is too low. I was heating my water to 10-12 degrees above target temp. He recommends 17 degrees. between grain absorption & the tun itself most of the heat dissipates within the first few minutes. This does go against what I originally said. That I was hitting my temp marks. Looking back I was hasty with my readings.
  2. I should not dump my sparge water (or lauter?) into the tun while draining the wort. The idea is to compact the liquid into the bottom of the tun thus compacting the sugars. I am stirring up the mash when I dump all sparge water in. We kept our sparge water 1-2 inches above the grain bed and our final results we excellent.

A 3rd recommendation he made was to lower the pH of the water. tap water is ~7 and the ideal mash pH is 5.2. He added a solvent, which I cannot remember the name of, which did this for us. I'll be picking up some of that this weekend.

Thanks to all who helped me out with this problem.

  • do the kits mention what efficiency their expected OG is based on?
    – mdma
    Commented Jan 28, 2012 at 1:25
  • 3
    There's no benefit to batch sparing slowly. With fly sparging it's important to go slow so as not to create channels in the grain bed. Likewise there is no advantage to leaving the sparge water for 30 minutes before draining. Add the water. Stir thoroughly and drain. Commented May 15, 2012 at 14:03
  • What Tobias said...
    – Denny Conn
    Commented May 16, 2012 at 15:40
  • interesting, because this is almost the opposite of what I told. I was told that a 30 minute rest wouldn't make a difference. the point of the strike water (?) is to stop the sugar conversion/extraction. so 0 min, or 30 min makes no difference. my quest for better efficiency continues. Commented May 16, 2012 at 17:18

7 Answers 7


you say that you let the sparge water sit for 10 mins then drain. That's a fast batch sparge. In your situation, I'd do this:

  1. recirculate the mash: drain off a half a gallon or more and add carefully back to the mash. If you have a pump, continual recirculation is ideal.
  2. after adding the sparge liquor, stir so it's thoroughly mixed and recirc a little also.
  3. leave for 30 mins minimum. It takes time for the sugars to leach out from the grain and into the sparge water. Cutting this step will reduce lautering efficiency. Feel free to leave it sitting for longer, but not less.

Otherwise, your process sounds good. Feel good that you made beer you like - everything else is just icing on the cake.

  • I think this is my next logical step easy to make these corrections and see if my numbers hit. Commented Jan 28, 2012 at 23:53
  • that's great to hear. good luck!
    – mdma
    Commented Jan 29, 2012 at 2:55
  • 1
    This seemed to make a difference. I also boosted the base grains from 6.5 to 8 lbs to get a bigger beer. all told I had 5.5 gal in primary and the SG was slightly higher than the directions calculated. expected more with more grain, but it may be a volume issue. that's next on the list to tackle. Commented Feb 27, 2012 at 0:45
  • 2
    I've never let the sparge water sit on the grains before draining. A good stir is needed to distribute the sugars, and a vorlauf is good to clarify the wort, but waiting accomplishes nothing. I get close to 80% brewhouse efficiency on normal strength beers with this technique. Commented May 15, 2012 at 14:06
  • 2
    I've experimented with it dozens of times and there is no gain from letting the sparge water sit before running it off. I simply stir in the sparge water an immediately vorlauf and drain. I average 85% efficiency.
    – Denny Conn
    Commented May 16, 2012 at 15:41

Could be many things. The first thing I would do is separate your conversion efficiency from your lautering efficiency. That will narrow down the problem.

The article at this link has some really great information on efficiency. It gets a little technical, but the chart in the Conversion Efficiency section is especially interesting.

enter image description here

What it's saying is to take a hydrometer sample of your first runnings. Then just match up your mash thickness with the gravity. So if you mash at 1.25 qt/lb like most brewers, you'd expect a reading of around 1.096. Your conversion efficiency should be close to 100% (I'm usually in the 95-98% range).

If you're far off, start with the crush. Are you milling your own? Try a finer crush and see if your efficiency goes up. Check your mash pH. Make sure your thermometer is accurate.

If you're 95-100% efficient there, time to look at your lautering process. Are you running off too much? Are you not boiling down far enough? Do you accurately measure how much pre-boil and post-boil wort you get? Are you taking pre-boil and post-boil hydrometer readings? The lauter efficiency section at the same link has more information as well.

So to tl;dr it, start with conversion efficiency. Make sure your volume measurements are accurate and take gravity readings before and after the boil. Then you can diagnose the problem.

  • grains are crushed from the vendor, but biol volume is definitely a factor. a play it loose in that regard. I have a measuring cup that maxes out a 4 cups. I use that to measure out gallons pre-boil, but I don't know by post boil until I transfer to primary. I'm still trying to figure out how to account for grain absorption and loss to mash tun & kettle. Commented Jan 27, 2012 at 23:11
  • i understood reads should be taken at ambient (68F) when transferring to primary. How would I take a reading pre-boil? Commented Jan 27, 2012 at 23:12
  • @JasonMeckley: I take the sample into a free-standing jar, and leave it until it cools under 100F. Then I take the reading, and use brewing software (Beersmith) to adjust the reading for temperature. I let it come down under 100F because readings get less accurate as temps go up.
    – JoeFish
    Commented Jan 28, 2012 at 0:18
  • 1
    A refractometer doesn't have this problem of needing the wort to cool, since the amount of wort is tiny compared to the body of the refractometer, and they are usually temperature compensated. You can get one from ebay for around $30. They work well for pre-ferment gravity samples. Post ferment, best to stick with a hydrometer.
    – mdma
    Commented May 16, 2012 at 16:28

I'd recommend double-checking your hydrometer and thermometer for starters, just to make sure you don't have an equipment problem. Secondly, for my own setup, the crush of the grain is the #1 factor in my efficiency. When ordering online (which I rarely do) my efficiency drops like the gravity on a sour ale compared to my bad-ass local shop's crush. So you might want to get your grain re-milled after it arrives, or try a local brew shop if you have one.

If you eliminate those possibilities, then what I would recommend for you is to simply throw in an extra 1-2 pounds of base malt into your recipes and keep on truckin'. I say this given that you say "They taste great", and if it were me, I wouldn't start messing around with my mash (which, if you mess up, can cause off flavors like astringency) unless my beers started to suck. CONSISTENCY is much more important than EFFICIENCY in mashing (in my opinion). And it looks like your gravities are all about the same % down from your target, so you'll quickly learn to compensate.

I had the opposite problem when I started doing all grain. I was shooting for 60-65% efficiency and got 84% on my first batch! (thanks to the Brew In a Bag technique.) I named that wheat beer my "Accidental Weizenbock".

  • I'm trying to figure out how to compensate :) I didn't think the vendor's crush would be sub-par. the Belgium double and Phat Tyre where kits. the Hopback was assembled at my local supply store. given that my efficiency is lower; how you would you compensate to boost effeciency? Commented Jan 27, 2012 at 23:05
  • Per my answer "simply throw in an extra 1-2 pounds of base malt". Or a pound or so of dry malt extract, which is what I do if my gravity seems off. I know where the 5gal point is in my brew kettle, so I'll pull a sample when I hit 5gal and adjust as needed by adding some dry extract.
    – GHP
    Commented Jan 30, 2012 at 13:43
  • OK, now I understand. I have always purchased kits, so I don't usually have extra ingredients. Commented Jan 30, 2012 at 14:27
  • Even with kits, its always good to keep a few pounds of Light Dry Malt Extract on hand for yeast starters and quick gravity modifications. I do All Grain exclusively, but still keep some LDME around for these purposes.
    – GHP
    Commented Jan 30, 2012 at 14:36
  • thanks for the tip. another excuse to swing by the supply store:) Commented Jan 30, 2012 at 14:54

Agree with everything on the great answer above, but isn't 1.25qt/lb a pretty thick mash? I'm off AG at the moment, trying to dial in some cool-side process issues, and never considered myself an expert, but I typically would shoot for 1.5-1.75qt/lb. I know on my first AG batch, I was off to about the extent you are and my Dubbel became a Belgian Brown/Single Abbey. IIRC, it was a water/grist ratio issue.

Also, doesn't the above chart assume that he is brewing with 100% barley and no wheat/rye/oats, which might have different starch conversion rates?

Are you using an brewing software to help with volumes? Not a Promash guy, but Beer Tools Pro helped me quite a bit with hot liquor/sparge volumes.

One other question, also mentioned in the above answer (which I voted for!) is have you measured pre and post-boil volumes? The 'suggested' OG reaidings from NB might assume a certain boil-off rate that you are not hitting due to your low rolling boil (which I've heard is good to do with wheat-based beers, but most others require a more vigorous boil).

  • i heard that a rolling boil is all you need, not matter what style. I used 1.5 with Phat Tyre (first AG) and SG measured low so I switched to 1.25 to get the thicker mash, assuming more extraction per unit of water. I have used 2 resources: brewmorebeer.com/all-grain-brewing-mashing and the home brewers calculator for my android. Commented Jan 27, 2012 at 23:09
  • 1.25 has been the standard for as long as I've been brewing. I usually use 1.5 qt/lb as well for easier stirring and elimination of doughballs. Which, @JasonMeckley, could be part of your problem as well. If you don't stir the mash well enough, you may get clumps of grain (doughballs) that don't get exposed to hot liquor (water).
    – JoeFish
    Commented Jan 28, 2012 at 0:21
  • Going by tradition, British beers are mashed around 1-1.5 qt/lb, which could be considered "thick". By contrast, German and Belgian beers are mashed "thin", from 1.5-2.5+ qt/lb. Thicker mashes leave more dextrinous wort, whereas thinner mashes dry the final beer out more. Efficiency typically goes up the thinner you mash, to a point. You can mash as high as 3 qt/lb (Brew In a Bag Technique) without any problems in the final beer.
    – GHP
    Commented Jan 30, 2012 at 13:53

Is the final volume of wort correct for the recipe? If your volume is high, your specific gravity will be correspondingly low.

Similarly, if you're leaving a lot of wort behind in the mash tun or brew kettle, then your efficiency will suffer.

In the end, it doesn't really matter what you're efficiency is. The important thing is to hit the same efficiency consistently, so you'll know how to adjust the recipe by adding base malt.

  • This is always the best place to start. You need to understand how much wort the tun leaves behind. Filling the tun with a measured volume of water, then draining it. The difference will tell you how much liquid you are leaving behind. That # is where you can leave sugar behind. Its compounded when batch sparging.
    – brewchez
    Commented Jan 28, 2012 at 0:46

Are you correcting your hydrometer readings for temperature? I hesitate to even suggest that, but your actual numbers look suspiciously off. If you assume that they were measured at around 145 F, then correcting gets you right at your target numbers.

  • the temp of the mash is ususally 70F before i take a reading. Commented Jan 27, 2012 at 23:01

If you're consistently getting the same efficiency then just add more grain. I brew in a bag so my efficiency is pretty low (65%) but it's usually around that figure. So I don't worry and just set that efficiency in beer alchemy before I formulate a recipe and go from there. It comes out okay and I make decent beer. The hot side is fairly forgiving so I don't particularly want to change my approach to alter my efficiency since it will add more time and more complication.

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