Need help with low efficiency batch sparge

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Need help with low efficiency batch sparge

Postby abo » Sun Mar 04, 2007 12:21 am


Two weeks ago, I tried my first all-grain brew, a basic pale ale. My batch sparge ended up at a low 55% efficiency. My mash was very thick -- almost like gruel. So I took good note that thick mashes were no good at converting starch.
Then yesterday, I tried to brew my second all-grain, a Belgian witbier.
Here's the relevant part of the recipe, in as much details as I can:
3.26 lbs Pilsen Malt
3.26 lbs Unmalted Wheat
0.47 lbs Oat Flakes
0.63 lbs Carapils Malt
1.60 lbs Common Sugar (I wanted it to be as pale as possible. So I added the sugar to get ~1.050 at ~2 SRM)
BeerTools tells me I should expect O.G.: 1.051 (at 65% efficiency)

Step Infusion Mash
Mash In:
11.55 litres (1.6 qt/lb)
Target Temp: 45 C
Debranching Rest: 20 minutes

Protein Rest: 40 minutes
Added 3 litres
Target Temp 52 C

Saccharification Rest:
Added 5.4 litres (and then, as needed, heated some of the wort with a pot on the stove)
Target Temp 57 C until iodine test indicates no more starch (~1h-1h15, with occasional stirring)
I used my primary fermenter to mash; the only vessel big enough.
At some time, it was in direct contact with the cold ceramic floor and
the bottom of the mash was probably near 45 C for some unknown amount of time.
This probably explain why this step took so long.

Total water: 19.95 litres

Batch Sparge
Transfered to my lauter tun, mixed the mash, waited 10 minutes, vorlauf and collected the runoff in the boil pot
Added 6.3 litres, again mixed the mash, waited 10 minutes, vorlauf and collected the runoff in the boil pot

I took a hydrometer reading of the second sparge running. 1.010
This surprised me a bit but I kinda assumed the lauter tun knew what he was doing

Collected around 20 litres. Boiled aggressivly for 60 minutes, cooled, added yeast and filled to 23 litres.
Took a hydrometer reading... 1.032!
Re-took a hydrometer reading... 1.032 again!
Shouted a few swear words... still 1.032!

BeerTools tells me I achieved a miserable 46% efficiency.
First 55% then 46%... This means that a few more batches and I will end up brewing soda for the kids!

I have read on the net that one can expect 75-80% efficiency from batch sparge. So does anyone understands why I got 46%, even though iodine reported complete conversion?

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Postby ColoradoBrewer » Sun Mar 04, 2007 7:24 am

I batch sparge and routinely get efficiencies in the 75-80% range. The first thing I would look at is your crush. Do you crush your own grain or have it crushed when you buy it? If you have your own mill try tightening the gap a little. I think mine is set at .039". You don't want a lot of flour, but a little is OK. If you buy your grain crushed ask them to run it through twice, or try another source. Also, don't obsess over efficiency. I agree that 46% is low, but once you reach the mid sixties you may have reached the limit of your system. Better to be consistent that get high numbers sometimes and not others. One last point, since you're taking your SG reading after topping off with water you want to make sure it is thoroughly mixed into the wort.
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Pale Ale

Postby brewmeisterintng » Sun Mar 04, 2007 8:55 am

I would have chosen a simpler recipe for my first all AG. Jumping right into a step mash as a result of unmalted grains is a bit much to start with. It would have been better to start with a recipe that had a base primarily of two row with a few specialty grains.
I too do batch mashing and always have get a consistent and on target OG.
Don't let this one batch discourage you but you might want to consider a simpler recipe until you get more comfortable with the processes.
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Postby slothrob » Sun Mar 04, 2007 10:35 am

Did you remember to add the sugar? I get 1.032 at 61% efficiency without the sugar.

Did you remember to correct your hydrometer resding for temperature?

You have a high adjunct to diastatic grain ratio. It should be enough, but as Brewmeister said, it's not a great choice for one of your first all-grain recipes.
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Postby abo » Sun Mar 04, 2007 10:58 am

I'm encouraged by your results! You are right about efficiency obsession. When I will end up with efficiency I expected, I will be a happy brewer.

I crush my grain with a corona mill. Since stuck sparges are not really a problem with batch sparge, I crushed my grains rather fine. 'Coarse flour' would better describe the grind than 'grains cracked open'. Next time I will stick with the standard crush size. A feeler gauge would be a nice addition to my brew tools.

As for your last point, no I did not mix after adding water. Very good point. Easily overlooked.


I just saw on BYO ( a top 10 hardest beer styles. On top of the list is Witbier!
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How to get a good crush with a corona mill

Postby abo » Wed Mar 07, 2007 1:28 pm

I have found on the net a very good way to setup a corona mill. This gives what seems to me a nice crush with most husk still intact.

The whole point is to crush the grain twice. Once at .070" and once more at .030". If you don't have feeler gauges (and if you have canadian coins) you can use a 2-dollar coin for the first grind (which is 0.070" thick) and use a canadian dime (.048" not close to .030" but still does a good job) for the second crush. When setting the thickness, make sure you maintain the grindstones parallel to each other, or the spacing will be narrower than you want it.

I hope this will be useful to someone!
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