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Author Topic: Partial mash/sparge size with full boil  (Read 3229 times)

Offline colinhayes

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Partial mash/sparge size with full boil
« on: August 02, 2011, 09:48:47 am »
Hi all,

So I'm changing up my brewing method to take advantage of the 3 gal MLT my friend has that I'm brewing with tomorrow.  I normally do BIAB in my 10 gal kettle, but we'll just be using that to boil this time.

So we'll be mashing 5 lb of grain at 1.5 qt/lb which gives us 1.875 gal of water in the mash.  Now before I've done ghetto sparge by placing the grain bags in a colander and pouring water over them, but we'll be doing a batch sparge with the cooler.  Beersmith says I'll need to collect 6.4 gallons of sparge to have enough preboil volume to hit my final target volume (90 min boil with 1 gallon total loss to kettle and fermenter means 7.75 gallons pre-boil).  Now, common sense says that 6.4 gal is WAY too much and that the pH will rise too much and we'll extract bad stuff.

My instinct is to just mash it, drain it, and sparge with ~1.5x the mash volume, or 2.8125 gallons (split into two sparges), and then top off with water in the kettle, which is what I've always done before since my capacity to heat sparge water was really limited.  Is my instinct right?  Could I get away with sparging more?  If I sparge more, should I adjust the pH of the sparge water?  I know sparging should stop when the runoff drops below 1.010, can I just sparge until this happens?  With his other kettle, we should be able to heat as much sparge water as needed, so no worries there.

Oy, what should I do?


Offline Jimmy K

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Re: Partial mash/sparge size with full boil
« Reply #1 on: August 02, 2011, 10:03:04 am »
I'm not sure if batch sparging with the full 6.4 gallons would hurt the beer, but I agree that it is not necessary. After sparging with 2.8 gallons in two sparges, all of the fermentables should be extracted from the grains. More sparging would take a lot of time with not much yield.
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Offline colinhayes

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Re: Partial mash/sparge size with full boil
« Reply #2 on: August 02, 2011, 10:08:54 am »
that's kind of what I was thinking.

If we can heat all the water we need before, then I won't have to add cold tap water to the kettle and wait another half hour for everything to heat up, which was a major annoyance.