Sparge volume vs. Efficiency

For the last 4 batches I've brewed, I have finally kept my equipment constant and it's really allowed me to dial in my process where it's repeatable, expected, and turning out beer that I enjoy. It also obviously makes for a smoother process, and I've enjoyed my brew days immensely more because of that (somewhat...I'll get to this later).

Now, with this said, I think I do everything right. I am a cooler MLT guy (48 qt Ice Cube) who does the double batch sparge method. Now, the way I have read is that you base everything off your boil-off volume: If you, say boil off 1 gallon per hour (just for the sake of sayin'), then you would want to start off with 6.5 gallons of wort to get to 5.5 gallons into the fermentor.

Now, I've been on a belgian kick lately, and thus I'm flying with a strict Pils base, so 90 minute boils for DMS reasons. I've calculated my boil-off to be around 16% an hour, and this is a value I have now dialed in repeatedly. Taking that into account I start with around 7.25 gallons pre boil.

This is where I get lost: I will sparge to this amount, and at the end of the sparge, I can still pull 1.040 wort most every session. I dial in my efficiency with my LHBS crush to around 67% as I usually do bigger than average beers. But this has happened mostly every time.

For the 888 I was pulling 1.040 wort until I was left with 11 gallons that I boiled down to 5.5. For my last brew day, a partigyle, I ended up (post-boil) with the small beer being 1.045 but I still pulled about a gallon of 1.040ish wort that I then canned for starters in the future. I didn't see how much volume it would have taken me to get down to 1.010 because I just wanted to start the boil.

So what's the true measure of efficiency? I could theoretically get 80-85% if I wanted to boil all day, but we all know we don't want to do that. But if I stick to my boil volume that I want, I'm around 65-67%.

Maybe a little long winded, but it's Friday morning and I have nothing better to do.

What say yous?

A little more info might get the discussion kicked off. What was your water to grain ratio, mash temp, sparge volume, sparge water temp, gravity of your first runnings, etc?

I regularly use 1.25qts/lb for the water to grain ratio. Most of the Belgians I mash at 152° and other styles I tend to mash at 154°. I usually don't have trouble hitting my mash temps.

My sparge volume will be the volume necessary to reach that pre-boil volume. I'll divide it in half and add two additions: dump one in, stir, vorlauf until clear, drain. Then repeat with the second half.

I haven't measured the gravity of my first runnings. I'll do that next brew.

Do you have a lot of dead space in your MLT so that after you drain the initial runnings there may still be a lot of high gravity sweet wort below your pickup?

Wait.. just to make sure. You are running off the mash prior to adding any sparge right? It doesn't sound right to me. My third runnings (after the second sparge infusion) typically reads 1.020 or lower based on a typical finished 1.050 or so beer. Surely a higher gravity beer will have a somewhat higher last runoff while you remain in reasonable preboil volume.

You make a good point though, anyone could hit 99% efficiency if they boil for 4 hours. I quote my efficiency numbers in the context of 70 minute boils and therefore limit the preboil volume to 12.5 for 11 gallon batches.

I always sparge with 1/2 gallon per pound of grain. On big beers it does take a lot of time to boil down, but I hit my numbers and thats whats important to me.

Bobby_M said:

Wait.. just to make sure. You are running off the mash prior to adding any sparge right? It doesn't sound right to me. My third runnings (after the second sparge infusion) typically reads 1.020 or lower based on a typical finished 1.050 or so beer. Surely a higher gravity beer will have a somewhat higher last runoff while you remain in reasonable preboil volume.

You make a good point though, anyone could hit 99% efficiency if they boil for 4 hours. I quote my efficiency numbers in the context of 70 minute boils and therefore limit the preboil volume to 12.5 for 11 gallon batches.

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Yes, I lauter before I sparge.

It doesn't sound right, that's why I'm asking. I could very well be the dead space, I don't really know how to calculate this...but I don't know.


Either way, if I'm at a terrible efficiency, I can just elect to boil down more or if I'm where I want to be, I have more starter wort.

The way to test deadspace is fill up the tun with water until it's just over your spigot. Then drain it. See how much gets left in the tun when it's stops draining.

When you fill up the MLT with your sparge water is the water reaching the top of the grain? I only do one sparge because of this and hit pretty good eff. numbers. Just to get this out there comma you are stirring the mash after the sparge water right?

sause said:

When you fill up the MLT with your sparge water is the water reaching the top of the grain? I only do one sparge because of this and hit pretty good eff. numbers. Just to get this out there comma you are stirring the mash after the sparge water right?

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I stir, but maybe not well enough. I need a paddle.