if im doing a 5 gal batch with 9# grain bill and im using 1.25 qt water per pound of grain how much water should i sparge with? Im asking this cause i always come up short when its time to fill a keg.
With my equipment I would mash in with ~2.9 gallons and sparge with 4.8 gallons giving 6.5 gallons in the kettle and boiling down to ~5.25 gallons for the fermenter. YMMV. Cheers!!!
If you’re batch slarging, just sparge with whatever amount it takes to get your boil volume. There will be no absorption on the sparge since the grain is already saturated, but you’ll have to account for any dead space in your tun.
Just a suggestion if your equipment supports it: for improved mash efficiency, I would mash in at a ratio of 1.5 and 2 quarts per pound. Then, as Denny says, just sparge with whatever amount you need to hit your pre-boil volume target.
In theory, your sparge volume will be approximately equal to your mash runoff, but I rarely worry about that. I think it’s more important to get your mash ratio right and don’t worry about the sparge volume as much.
One more tip: there is software (e.g., Beersmith, Promash) and free calculators you can use online to approximate what your water volumes should be (factoring in grain absorption, boil off volume, etc).
