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Grain absorption?

Mashing
#1

So after about 8 batches of All Grain, I continue to struggle with the amount of sparge water. Either I end up with too much in the kettle, or too little. When I get too much I seem to miss my OG too low. When I get too little, I have a smaller amount in the fermenter.

So I got to thinking, could it be as easy as this: Do the mash with whatever iSparge says to do, let’s say 13lbs grains, means apprx 4 gallons mash water. Drain it off, say I get 2 1/2 gallons of Wort. Then can I just assume that the grain has absorbed all the water it can, so now I just decide how much water I need to get me to a 6 1/2 gallon boil. so that means dropping in another 4 gallons, batch sparge, drain and I should basically get all 4 gallons out, right??

#2

Yes, it’s as simple as that as long as you account for any differences in draining the mash and the sparge. For instance, I typically just drain the mash to the point that it starts to pull some air through the braid, close the valve, add the sparge, then drain the cooler dry, so I’m leaving a gallon or two of liquid in the MT before adding the sparge.

#3

Are you fly sparging or batch sparging?

Fly Sparging, fill your hot liquor tank up and keep it going until you reach your boil level in the pot and shut it down. You can leave some wort behind, it shouldn’t affect the efficiency.

Batch Sparging, put about 1/2 gallon more than what you would need after you drain off your first wort to reach your boil level, let it sit a few mins and drain off until you reach your boil level. Then stop sparging. Again, shouldn’t affect your efficiency.

#4

With batch sparging it is ideal to drain it completely. If you don’t drain all the first runnings the sparge gravity will be higher. The gravity of the last sparge is what is lost in the grain and dead space.

My grain absorption is one half quart per pound. My MLT has no dead space. It’s simple to figure the needed volumes. I normally strike half the boil volume plus grain absorption and sparge with the other half of the boil volume.

#5

As I said, after you run off your first wort and fill again to empty, if you leave a little wort behind after this step, it wont affect efficiency much.

If you don’t believe me do the math yourself.

Estimating Lauter Efficiency (Batch Sparging) on

http://braukaiser.com/wiki/index.php?ti ... h_Schedule
#6

I’m not sure what you mean? If you leave any sparge water behind you lost some gravity (unless you sparged to zero). The math is simple, volume (grain+dead space+left over) x gravity = gravity points lost.

The iss the about the same formula but the total sparge is the volume. It’s dilution of absorption and dead space. Completely draining the first runnings lowers the sparge gravity, thus lowing the loss left after the sparge. The bigger the grain bill the more that can be lost because both the absorption is more and the gravity is higher.

Conversion has by far a greater impact in overall efficiency. Kai shows only a 8% loss going from a single sparge to no sparge.

#7

As I said it wont affect it much.

If you have 13 lbs of grain with 0.5qt/lb absorption and 1qt left behind and use normal 1.33 water to grain ratio you get:

First Efficiency 56.5% = 100%*9.75qt/17.25qt

2nd Efficiency with no added water 25.1% = 43.5%*10.25/17.75

2nd Efficiency with 2qt added water 24.4% = 43.5%*10.25/18.25

Therefore your overall efficiency is 81.6% for no added water and 81.9% for adding a half gallon.

Change of .7% = not much. Then you will never worry about not reaching your boil volume. There are a lot more variables in how much water grain can hold, and also what is left behind, all I am saying is if you add more water, you wont have to worry about not making your volume and it wont affect efficiency much.

#8

I don’t like the idea of having extra that I just waste. This is what I noticed last time, I had about 1 extra gallon of sweet wort that I had to dump. I decided to take a gravity reading on it for s & g’s and it was at 1.020.

I have yet to actually determine what my efficiency is. This next batch I am gonna try to figure that out. I know there are some calculators out there for all that. My MT is the 10 gallon round cooler with a steel braid filter inside, very little gets lost in the MT, maybe 1/2 gallon tops. If I tilt it, I think most everything comes out.

Thanks for the good ideas.

#9

As with everything, more water will reduce your efficiency, but a little really wont hurt anything. With a few points difference in the end, I am doubting that you will notice a difference in taste, worst off you will have to drink one more to get drunk.

There are many people who think that this is a hard science and that every little drop of wort counts. I am one to say that, although there are equations and measurable amounts all along the way, that little changes and OOPses wont change the fact that now you have beer and before you didn’t.

Remember, when you are brewing, you’re brewing to your tastes, and if you like the end product that is all that is important. (Unless you’re competing)

#10

Figuring the water volumes before hand is pretty simple. There is always Denny’s method, drain then measure the difference needed for boil volume and sparge with that. The best way to get consistent BHE is to consistency get high BHE. Losing some here and there increases the margin of error.

#11

If you fixate on getting every little bit of wort you’ll drive yourself crazy worrying about something that doesn’t really matter. The water you add for the second rinse is the difference between what is in the kettle, and what needs to be in the kettle for the full boil volume. It’s that simple.

If you drained your mash tun into the kettle there will usually be some wort left after the first draining, that there is exactly your system’s mash tun waste. For the second rinse you are adding a set volume as the grain is already saturated, so that little waste amount will be the same on the second draining. So, it is automatically taken into account on a batch sparge.

In my system built with kegs, that’s about a quarter gallon at most and although it is in my overall calculations, it really is not something that will make or break my recipes.

#12

A long time ago an old brewer friend told me to keep collecting until the gravity of your runnings reaches 25% of the first runnings gravity. Example…if your initial runnings were 1.060 then you can keep collecting until you hit 1.015. That is what I have done all along and have usually hit my projected OGs post boil as predicted using ProMash and other brewing software. I dont worry too much about numbers unless they are way off and using this method allows me to make sure that I end up with exactly what I want in the boil kettle and the kegs. Any extra wort that I have pre-boil I put in jars and freeze to use for starters later.

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