For the few years I've been brewing AG, I've used batch sparging with a 70qt cooler. But this year I've built a new brewery which is equipped for fly sparging, so I'm trying that.

With fly sparging, I understand sparing should be stopped when the SG below 1.010 (or the pH above 5.8). But With the lauter tun full of 1.010 wort at the end of sparging, doesn't that hurt efficiency compared to other forms of sparging?

  • 1
    If you were to refill your mash tun after the second running (so a third 'batch') and measure it, it would probably be close to 1.010 or so. So the two methods are pretty close to whats being left behind. I have done a few runs with a third sparge so I am speaking from some experience. – brewchez Aug 28 '11 at 2:22
  • 2
    @brewchez: So fly sparging wastes a tun of water? When you hit 1.010, do you turn off the sparge arm then run what's in the tun down the drain? (I've never looked into fly sparging.) – JackSmith Aug 28 '11 at 2:33
  • 1
    Yep. When the run off gets down to near 1.010 you have typically collected all your preboil volume in the kettle. So the grain, water and sugar in the tun are thrown out. I never thought of it as wasting another batch of water though, but I guess it is. – brewchez Aug 28 '11 at 12:56
  • 1
    I'm no expert, but I've witnessed four or five fly spargers in action. Seems like about half of them left the mash tun full of water when they quit pulling from the mash tun, but the others had a limited amount of water in the hot liquor tank in the first place, so fly sparging stopped, the level in the mash tun went down low or emptied. Do these two techniques have different names? – Dale Aug 28 '11 at 13:12
  • 2
    I suppose if you knew your system really well then you could stop adding sparge water and let the tun drain out as you collect the last of your pre boil volume. But there is no special term for that as fas as I know. – brewchez Aug 28 '11 at 17:27

The sugars left behind in a batch sparging scenario are generally the same as in a fly sparge set up. The only difference is that in batch sparging there is no water left in the tun. In fly sparging the tun is filled with water. But the net effect on efficiency is the same. If you were to go and fill the batch sparged tun up again, as if to do a third run off, it would be at or around 1.010. You can't get all the sugars out regardless of method being used. 100% efficiency does not make the best beer either.

So no, its not hurting efficiency over other forms of sparging.


Ideally, your flow rate into your mash tun would be at or less than your flow rate through the mash and out into your kettle. In this case, liquid shouldn't be collecting in your mash tun, and when you hit 1.010 SG in your kettle you can simply stop adding sparge water. The slight "in flight" load still making it's way through the mash at that point shouldn't be enough to hurt your numbers.

If your flow rate through your mash is painfully slow, you might look at your lauter geometry and see if there's some improvement to be made. Also rice hulls can loosen up a thick mash.

  • If you have a 5 gallon mash volume (grain and water), after fly sparging don't you still have a 5 gallon mash? Its just less most of the sugars. The water volume within the mash hasn't really changed much post a successful fly sparge. – brewchez Sep 6 '11 at 17:22
  • Thanks for answering. I understand having the flow rates the same, but if the flow rate into the MLT is less than the outflow that will mean some grain is not under liquor. I'm not using a sparge arm, so the exposed grain will not be sparged effectively. – mdma Sep 12 '11 at 10:32
  • I don't think grain needs to be entirely submerged during sparge in order to rinse the residual sugars. I think water constantly flowing past the grains is sufficient. – Jonathan Hanson Sep 27 '11 at 9:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.