How Do I Sparge This?

[melinda]

G'day Men,
I've got a problem with this stout I'm making. Here is the grain bill:
4 kg Marris Otta
1.7 kg Carapils
1.7 kg Crystal
1.62 kg Wheat Malt
.45 kg Roasted Barley
.225 kg Black Malt
OG 1.115
FG 1.037
My preboil volume is 39 L. If I multiply the grain by 2.5 to get my water to mash with I get 24.2 L. This only leaves 14.8 L to do 2 sparges. How do I get around this? Do I only do one sparge?
Any advice would be good because I'm keen to get this bottled for next year.
Thanks,
Cadbury

 

[Wolfy]

If - for your equipment - multiplying the grain by 2.5 to get the mash water works for for you then sparge once only.
However - for my setup - I'd be looking to use about 25-30L mash water and then another 25-30L for sparge (working on the assumption the grain will retain 10-15L of water).

 

[manticle]

What's wrong with one sparge?

Haven't calculated myself but as wolfy suggested - have you calculated losses in there (incl grain absorption)?

 

[Swinging Beef]

Why not fly sparge manually, just this once.

 

[melinda]

thanks for that. I thought there may have been some scientific reason that you had to do ex amount of sparges. Thanks for the info, I'll get started.
Cadbury

 

[Wolfy]

I recall reading something suggesting that the more times (up to about 4-5) you sparge (when batch sparging) you'll get slightly better extraction - but I think that's about as scientific as it gets.

 

[manticle]

Balanced with extracting tannins from oversparging or is that just if you're trying to get extra volume?

Personally I sparge once if I can, bigger grain bills get two but efficiency is pretty consistent across the board.

 

[Thirsty Boy]

You could always sparge more and boil for longer to get the volume back down.

The lack of ability to sparge with the normal volume, amongst other things, is why batch and no sparge brewing techniques always get lower efficiency with increased grain bills and higher wort gravity.

I think its highly likely that you will get noticeably, if not significantly lower efficiency on this batch than normal... I would have some dme and sugar on hand just in case.

 

[manticle]

Not sure I follow you TB. You mean sparging once rather than twice will give drastically lower extraction or trying to split up 14 L into two sparges?

I batch sparge - generally once but sometimes twice and regularly get 70-75 % efficiency. Certainly no need for extra DME - almost always hitting my targets within a point or two and ocassionally overshooting between 5 and 10 (could be many factors that one obviously including boiloff).

I know fly sparging is meant to lift efficiency but why the necessity for DME on hand?

@ Cadbury: Actually now I'm very confused. What is the post boil volume? How do you get 1115 from 4kg base malt? Will the truckload of crystal really add that much? What kind of stout recipe are you making that requires nearly 4 kg crystal?

I also just ran through the figures and you haven't allowed for grain absorption so your sparge amount is incorrect (as wolfy pointed out)

 

[Thirsty Boy]

If you use less sparge water, you will get less efficiency, regardless of whether you sparge once twice, a dozen times or continuously.

Batch spurges and all forms of sparging that rely on diluting the total pool of sugars and draining out, rather than rinsing continuously - must - as a physical truism, get lower efficiency when the wort being drained out is of a higher gravity, and more grain is in the mash tun. This is exacerbated the less times you sparge.

I used sparge with a single full volume run-off and regularly got 75%, 78% if I bumped it to two run-offs... So I am not suggesting that cadbury will get "bad" efficiency from a raw numbers perspective, simply that he is quite likely to get worse efficiency than he would on a normal gravity batch, that he should perhaps anticipate that & and that a bit of DME on hand is always a nice insurance policy when you are brewing outside your normal parameters.

TB

 

[manticle]

I should apologise. When I wrote that bit of the post, I hadn't taken a really good look at the high OG and large amount of malt - just saw 4 kg marris otter and neglected to notice the amounts of crystal malts in there. That thick a mash? yes I'm with you.

 

[vykuza]

I recall reading something suggesting that the more times (up to about 4-5) you sparge (when batch sparging) you'll get slightly better extraction - but I think that's about as scientific as it gets.

Braukaiser did the hard yards on batch sparging and efficiency, starting around slide 15. It's a slide deck from a talk though, the data is presented but you'll have to make up your own narrative. He includes data for no, 1, 2 and 3 sparges.

A quick summary is:
No sparge to 1 sparge == 8% increase in extraction efficiency
1 sparge to 2 sparges == an additional 3%
2 sparges to 3 sparges added an additional 1%


I'm not doing the data justice with this short explanation, so have a read through the whole thing.

PDF link here: Kai Troester - braukaiser.com

Edit: Here's the page from his site with the data graphed against different grist sizes and the number of sparges.

 

[goomboogo]

Cadbury, do you really want 17-18% carapils in this beer? And the same percentage of crystal (what sort of crystal?). Did you happen to get this recipe from an American source? I suspect the sparging isn't going to be the biggest issue with this beer.