Gerry_P
Well-Known Member
If you're batch sparging it shouldn't matter how fast you drain the mash tun. You should mix the sparge water in really well and then all of the sugars left in the tun will be evenly distributed and dissolved in the water. So as long as you get all of the wort out, it doesn't matter if it comes out fast or slow. That's one of the big advantages of batch sparging.
Maybe you're talking about fly sparging though, in which case the flow rate does matter.
My understanding is that batch sparging should be drained slowly because it allows for more sugars to be extracted from the grain bed as the liquid passes through it on the way out. Or maybe it was to avoid stuck sparges. Idk, I might be wrong but it seemed like a good idea and it didn't cost extra.
Anyway, here's what I did: the previous batch was either "no sparge" or "batch sparged", depending on who you listen to. Mashed, recirculated, didn't drain anything, added hot sparge water, stirred, let settle, and drained pretty fast. It took maybe 10 minutes to drain, maybe a little more, and my brewhouse effciency was 61% (I thought it was 63% but I had confused it with a previous BIAB batch.)
Last batch I had my mash tun almost filled, so I recirculated, then started draining the mash slowly while adding sparge water. I didn't drain the mash down to a level just above the grain bed as you're supposed to do when fly sparging. Eventually all my sparge water was in the mash tun, and I just left it draining slowly. The whole thing took about 30-40 minutes, iirc. I ended up with 73% brewhouse. Idk what you'd call that..."fly batching", "flatch sparging", or maybe "lazy man's fly sparge"... I thought I made it up, but as it turns out this guy beat me to it almost 7 years ago: https://www.homebrewtalk.com/showthread.php?t=75454