I’m going to try a batch sparge next and am wondering if these numbers make since.

I’ve got 9 lbs of grain.

I want to do a 2 running sparge.

9lbs * 0.12gallons = 1.08 gallons of grain absorption
0.50 gallons for dead space under false bottom.

I’m shooting for 6.75 gallons for preboil for a 5 gallon batch.

That means I would want to get about 3.37 gallons per running for best efficiency.

3.37(what I want) + 1.08(grain) + 0.50(dead space) = 4.95 gallons to mash in

After first runoff add 3.37 gallons back in mix and runoff again.

So a total water volume of 4.95 + 3.37 = 8.32 gallons needed for brew.

It makes since in mind but then again…

I’m using a 10 gallon rubbermaid cooler for my mash tun. The one thing that looks kind of off is the second sparge water. Is 3.37 gallons enough to put the grain back into a solution?

I doubt you have 1/2 gallon dead space under your false bottom that will be left. Put some water in your mash container and drain all the way through the hose you will use and then see what is actually left. Most pickup tubes leave less than a 1/4 gallon.

Keep it simple, if you calculate your grain will absorb roughly a gallon, and you start with a total of 4.95 gallons to mash-in, then you are getting 3.95 gallons out for the first runnings.

In a perfect world, if you need 6.75 at the start of boil after sparging, then you are adding 2.8 gallons for the sparge, plus you can add in the loss of the 1/4 gallon for 3.05 for the sparge.

Make it even easier… If you drain the first runnings into the kettle, then measure it, your sparge is the difference between what you have and what you need to get your pre-boil volume. Don’t over-math this. You’ll find that even if you round your numbers a bit it all works.

Once you get the hang of it you can do it all by eye and still be dead-nuts on your numbers.

HA! Thanks for the change in grammar, it makes cents…
That’s what you get by typing to fast on a brew forum while try to fix problems at work. The brain doesn’t work, especially when you use the same word incorrectly more than one time!

I also appreciate the advice on the sparging. Cents this is my first batch sparge I’ll probably do the run off and just add the difference to the mashtun. It will give me a good base line to use for the future.

THIS^^^^! Rather than guess at the numbers, do it this way the first few times and find out what the numbers really are. Altho9ugh I’ve got the numbers down pretty well after all these years, I still measure my mash runoff volume to be sure I get what I intend.

THIS^^^^! Rather than guess at the numbers, do it this way the first few times and find out what the numbers really are. Altho9ugh I’ve got the numbers down pretty well after all these years, I still measure my mash runoff volume to be sure I get what I intend.[/quote]
I run mine into my bottling bucket. It has graduated gallon marks on it.

I have my mash paddle marked with gallon graduations matched to my kettle. I just run off into my kettle and use the paddle to measure approximate volumes and be sure that I am getting the right pre-boil volume.