# Help with Mash/Sparge Volume Calculations



## Bob_Loblaw (26/11/15)

Hi All

I'm attempting my second brew on the new Keg King Robo Brew and I think I messed up my mash and sparge water calculations last time coming up a little short on fermenter volume. Can someone help me with my calculations on the following?

Batch Volume - 23ltrs in the fermenter
Total Grain - 5.57kg
Total Hops - 140gms

Using a few calculators around the net brought me to a mash volume of 13.9L

I then assume I will need to sparge with 16.1L of water to bring my pre-boil volume to 30L factoring in a 15% evaporation rate during the boil. There is 3 litres of dead space beneath the outlet of the Robo brew so this should give me 23L of wort right?

I'm looking to do a single mash (will move into stepped mashes later) so if I have this right my mash schedule should go as follows:


Mash in at 67C with 13.9L - recirculating through the pump I will be buying this weekend
Mash out at 75C
Raise the malt pipe and sparge with 16.1L of 75C water giving a total pre-boil volume of
30L

Am I forgetting something? I feel like I should be taking into account the amount of water the grain will soak up and hold onto after mashing and sparging.


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## Yob (26/11/15)

+1L/kg grain + any kettle losses you normally get


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## gap (26/11/15)

Bob_Loblaw said:


> Hi All
> 
> I'm attempting my second brew on the new Keg King Robo Brew and I think I messed up my mash and sparge water calculations last time coming up a little short on fermenter volume. Can someone help me with my calculations on the following?
> 
> ...


You will find the grain will absorb water during mash which it will not give back up , so you will also lose some volume to that.
You coud start at 1.00 litre per Kilo of grain and adjust as your note the difference after a few brews.


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## Bob_Loblaw (26/11/15)

So I should add this into my sparge water amount right? Roughly 5.5L more.


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## Bob_Loblaw (26/11/15)

Actually, as the Grainfather and Robo brew are similar systems I looked up their online calculators. This is what theirs comes up with:

Mash & Sparge Water: Batch Volume (L): 23
Grain Bill Weight (kg): 5.57 

*Mash Water (L): *
18.54
*Sparge Water (L): *
13.92


Looks like they take into account 1L/kg of water lost to grain.

32.46L of total liquor - 5.57L to grain = 26.89L at boil. Take 15% of that for evaporation and you have 22.85L.

Sounds legit.


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## gusty (27/11/15)

Hi bob, just try say a grain to water ratio of 3L/Kg, for this brew that's 16.7L of strike water, then you will have to add your boil off water to your final 23L witch should give you 26.6L pre boil?. So sparge with 9.9L, this is sort of how I use to work mine out, all I did was just sparge till I hit my pre boil volume. I don't think your system will have a dead space because it's in one unit??, but you will have some turn/hop loses, I use beersmith as my calculator and it's been a great investment, just needs to be setup and it's very handy!


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## Dan Pratt (27/11/15)

your grain absorption is one thing to get dialled in when brewing. also to calulate the loss of wort to the hop additions.

I tend to use the 12mls per gram and that gets me my target. 140g x 12mls = 1.68lts lost to trub at the end of the boil.


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## antiphile (27/11/15)

This one only makes about 1 litre of loss, but while cooling the wort from the boil to pitching temp, you can also expect the volume to shrink by about 4%. So if you end up with 25 litres immediately post boil, you'll only have 24 litres in the fermenter (ignoring any other losses through evaporation etc).


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