Gravity and Sparge Questions

I will be doing my first AG brew this weekend and have a couple questions before I give it a go.
I am going to be mashing in a 5 gal. water cooler. When it comes time to sparge i am planning to use 5.4 gallons (batch sparge), my grain bill is 10.75lbs and .5 gal/lb right? Since i only have a 5gal capacity i was going to split it into 2 sparges. My question is how long to let each sparge rest? I was thinking 30 min or so.
Also, when do I need to take my Gravity readings? I was going to take one post boil as it went to the fermenter so I can figrure out alcohol and such. I guess I'm not sure what readings I need for efficiency. It would be nice to see how I do my first time out.
Thanks for any help!

I batch sparge and never let it rest more than a few minutes. Basically add the hot water, stir it up, and let sit a couple minutes. Vorlauf and drain. Then repeat.

I take gravity readings at 1st runnings, preboil ( so I know I'm close ), and then every 30 minutes to see if my post boil is going to be where I need it. This is where software like Beersmith comes in handy, as it estimates your preboil gravity and allows you to adjust if needed.

Since the total water you are mentioning is 5.4 I'm assuming you are going to be doing the mash and sparge with the total amount of water. You want to use 1.25-1.5 quarts per lb of grain. 10.75 x1.25 =13.43 quarts =3.35 Gallons. So you would bring 3.35 gallons up to strike temp and mash in with that. You will loose about .1 Gallons per lb of grain. So you will loose about 1 Gallon to grain absorption.
2.3 Gallons will come out and you will need to use the rest for sparging. So with the volume of your MLT you should be able to use the full amount from there until you reach the 5.4G for your boil.

The simple way to figure the sparge volume is to see what you get from your first runnings (the volume that comes out after draining your Mash tun after mashing) and subtracting from what you want your pre-boil volume to be:

e.g. I want 7 gallons preboil. I got 2 gallons of first runnings. Therefore, I need 5 gallons of sparge water total.

You can measure a sample of each running individually, but I usually collect my total volume of pre-boil wort and measure that instead (after mixing it) as it is coming to a boil.

Thanks for the input! I was going to mash with 3.35 gal and figured on losing a little over a gallon to the grain so I would end up with just a little over 2 gal of wort. Then I was going to sparge with the 5.4 gallons so total collection would be just over 7 gallons pre-boil, which is what i was shooting for. Then I will just boil it down to 5.5 or so to go in the fermenter. Sounds like I'm on track.

Also I read on Palmers web site some info on calculating effiency so I think I've got that covered.

Stevo: Thanks for the info, That coult save some time on brew day. I'll Just go 10min or so then.

Thanks again everyone.

Barnstormer said:

Thanks for the input! I was going to mash with 3.35 gal and figured on losing a little over a gallon to the grain so I would end up with just a little over 2 gal of wort.

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I'm going to predict that you lose a little more than 1 gallon (that is just shy of 0.1 gal/lb grain). You also need to account for Mash Tun dead-space which can vary considerably.

Barnstormer said:

Then I was going to sparge with the 5.4 gallons so total collection would be just over 7 gallons pre-boil, which is what i was shooting for. Then I will just boil it down to 5.5 or so to go in the fermenter. Sounds like I'm on track.

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for your first time, I'd heat a full 7 gallons of sparge water....nothing worse than not hitting your pre-boil volume and have to wait for more water to heat up. After this you can figure out how much water loss you have on your setup.

Barnstormer said:

Stevo: Thanks for the info, That coult save some time on brew day. I'll Just go 10min or so then.

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Just FYI, I don't even bother to wait 10 minutes; I add the sparge, mix like hell, then open the valve to start my vorlauf.

Thanks, I really appreciate the tips! Hopefully I will be brewing this Saturday. I will definately use your advice and let you know how it comes out!

broadbill said:

I'm going to predict that you lose a little more than 1 gallon (that is just shy of 0.1 gal/lb grain). You also need to account for Mash Tun dead-space which can vary considerably.

for your first time, I'd heat a full 7 gallons of sparge water....nothing worse than not hitting your pre-boil volume and have to wait for more water to heat up. After this you can figure out how much water loss you have on your setup.

Just FYI, I don't even bother to wait 10 minutes; I add the sparge, mix like hell, then open the valve to start my vorlauf.

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+1 to all of this. Grain absorbtion is usually closer to 0.125 gal/lb (assuming a decent crush), but it's better to just see what your first runnings are, and subtract from your desired PB volume to figure out how much to sparge with, especially since you don't know what your system losses are yet. You'll have to vorlauf a little more if you don't wait for the grain bed to settle, but it's still way faster than waiting for 10 min.

I don't think it's really necessary to think much about this issue..

I use 5 gallon round coolers for sparge and mashing, and I fly sparge. You don't need to calculate EXACTLY the perfect sparge amount, or grain absorption, or whatever - you just want to sparge enough to get to a given volume of wort - like 6.5 - 7 gallons or whatever.

To accomplish this, first of all, I ALWAYS fill the sparge water up to maximum. Next, I simply add an additional 1/2-1 gallon of boiling water to my mash at about the 60minute mark. It's not enough to mash out with, but increases the volume a bit and raises the temp up a couple degrees (insignificant at this point in the mash). I do this mainly to help ensure that I will have more than enough water to drain through the mash.

When I start draining, I just make sure I have several inches of water above the grain bed, and I close the MT valve when I've gotten the required volume in the kettle, and I generally have water left. Better to have more than enough, than not enough. It really sucks to run out of sparge water and miss your wort volume.

Go ahead and calculate that you need exactly 4.23 gallons of sparge water, or grains absorb X amount or whatever - but you should just fill it up with more than enough and use what you need.

This!

I routinely fell short of my boil volume until I just started heating "more" than I needed and then could just fly-sparge until I have the right amount of wort for the boil. Then I used the left over for cleaning water... Convenient and, honestly, I only had an extra gallon or so of water so not bad anyway...