When to stop the sparge?

The gravity in the kettle should end up being lower than your predicted OG. This is because during the boil the wort is concentrated. I think it will end up being a matter of dialing in your process with your equipment to reach your expected values. I would say to stop once your volume in the kettle is enough to reach your post boil volume accounting for evaporation.

 

or...you can just go here and fill in the blanks..

http://www.brew365.com/mash_sparge_water_calculator.php

i always mash in @ 1.25qt per lb of grain....

and yes....dial in your equipment!

 

With batch sparging, you add exactly the amount of sparge water that you'll need. So you stop when it stops running. Get some good software or a spreadsheet to make it easy to figure out.

Adding more sparge water than you need and then stopping once pre-boil volume has been reached will result in lower mash efficiency.

 

Almost. You also need to account for grain wort absorption (roughly 0.12 gallons per pound, YMMV ) and mash tun deadspace loss (which will depend on your particular mash tun).

ETA: Half a gallon of boil-off (assumed by your 5.5 gallons pre-boil target for a 5 gallon batch) is probably somewhat low. Then there's also hop wort absorption.

 

To piggy back on @VikeMan you will want more like 6.25-6.5 gallons pre boil, this will account for about 1 gallon of boil off over an hour long boil (standard rate) and for hop absorption as well as kettle dead space (what your pick-up tube or siphon can't get in the bottom corners of the kettle). If you are doing a lightly hoped beer closer to 6.25, if an IPA or IIPA you will want to account for a higher loss to hops so closer to 6.5 or more.

 

I always forget to mention kettle deadspace, because in my setup there is none.

OP: Any competent brewing software will have brewhouse parameters for all of the losses discussed in this thread.

 

Yeah, as you get some data from your all-grain batches, you will be able to dial in your parameters more precisely. I wouldn't worry too much about hitting OG on the nose for your first couple of all-grain batches - just getting in the neighborhood should be fine. (By which I mean, do the math properly, but don't worry if some of your assumptions turn out to be off by a little.)

One nice trick, though, is that you can calculate the total amount of gravity in your kettle, which stays constant throughout the boil (since sugar isn't entering or leaving the kettle). So for instance, let's say I've collected 6.25 gallons of 1.040 wort. I can calculate that if I boil off 1.25 gallons, I will have 5 gallons of 1.050 wort. Now, I won't actually be able to collect the entire 5 gallons (there will be some trub, and some liquid will be absorbed in the hops), but once I know the total gravity, I can determine what gravity my wort is just by measuring its volume.

Here's how the math works. The total gravity is the decimal portion of the gravity reading (so 1.055 becomes 55, 1.110 becomes 110, etc.) multiplied by the volume (I use gallons, but I suppose you could use whatever volume unit you want). So when I collected 6.25 gallons of 1.040 wort, I had 250 units of gravity (6.25 * 40 = 250). When I had boiled away 1.25 gallons of water, I still had 250 gravity units, but now it is dissolved in 5 gallons, so the wort would measure 1.050 in gravity.

So once you've done your sparge, you might consider taking a gravity reading of your well-mixed wort. (Remember that temperature affects the gravity measurement. I usually cool a sample to room temperature and then take a reading.) If you can calculate the volume you have collected, and you know the gravity reading, you can calculate the total gravity in the kettle. Then you can figure out what your OG will be if you boil off x gallons of water. At that point if you are too far off the mark you could make some adjustments - add some DME if you are way below your target gravity, water it down (or do a shorter boil) if you have too much gravity.

But again, for your first few brews, I wouldn't worry so much about hitting the OG precisely. Just make sure to measure carefully so you will know what to expect for future batches.

 

Definitely when your last runnings bottom out close to 1.010...but u probably won't know that at the time so use a calculator (as others have suggested) that will get u close and then RAHAHB if possible.

edit: I almost never drink on brew day untill yeast is pitched.

 

He's batch sparging. The runnings will be the same gravity throughout the sparge.

 

Once you know what you need pre boil volume, it's easy to figure out what else you need after you lauter your tun and take the 1st runnings.

Need 7 gallons, and collected 3 with the first runnings, then you need to sparge with 4 gallons.

Brewing software will help you get the handle on it, and you'll figure out all the specifics over time once you learn your system.

 

Most people double sparge...the second one should be much lower.

 

Do they? I would have said single batch sparging is more common. At least for low to mid gravity beers.

If he does double batch sparge, the runnings from the second one will be lower than the first. But they won't vary from the beginning to the end with each sparge. So there's no reason to monitor the gravity of the runnings and declare some cutoff point.

If you double batch sparge a small beer, you can indeed (depending on volumes of each sparge and other parameters) end up with a very low OG last runnings (and so depending on the water used, could run into pH/tannin extraction issues). I don't recommend double batch sparging low gravity worts.

 

I agree with VikeMan, the only time I would double sparge is with a heavy grain load. A normal 1.050 beer I just don't see getting enough sugar in the second wort to stop tannin extraction and other unintended flavors.

 

''the only time I would double sparge is with a heavy grain load"

OR a regular 10 gal mash tun, IMHO...I realize there are some massive mash tuns out there, but for the rest of us "marginally endowed", double-sparging is almost a necessity...AND accomplished safely with the proper ph sparge water.

 

Stop sparge when it feels right man.