When I was taught all grain by a friend I was told it was important to not disturb grain bed when adding the sparge water. But been watching vids and reading lately and it appears some do stir up grain bed when adding sparge.
In my opinion, you should not disturb the bed once the bed has been vorlaufed and runoff begun. Stirring the bed means that all those fines that were immobilized near the top of the grain bed during the vorlauf, are now mobile and in the wort. They would then be carried into the kettle where they can do damage to your beer.
If there is a concern that your bed is becoming ‘stuck’, I find that its often because of formation of a schmutzdeck (dirty layer) at the surface of the bed. Some brewers like to ‘cut’ their bed with a knife, but I believe that gentle mixing of that layer into the upper inch or two of the bed, will improve permeability better than cutting.
I’m not sure that’s true. Batch sparging is pretty much just like fly sparging. The difference is how and when the sparging water is added back to the tun. Mixing shouldn’t be required.
After I drain the first runnings the grain bed is really compacted so I add the sparge water and stir to loosen it up and make sure that all of the grain is exposed to the sparge water so it can carry off more sugars. I really never thought of not stirring, but may try it just to see how extractions compare between the 2 methods. Wouldn’t be the first time I’ve been wrong. and likely not the last.
I batch sparge, and don’t usually stir. Actually, I also try to disturb the grain bed as little as possible. I’ll double a sheet of aluminum foil with holes poked in it to disperse the sparge water gently. With my new tun, I have a recirculation manifold to accomplish that (it sits on top of the grain bed and the water flows out the top).
I have not noticed a difference between cutting with a knife like Jeff or mixing up the top like Martin. I do one or the other when I run on the first of the sparge water.
(I sparge. I don’t know what to call it, because I do what commercial brewers called batch sparging before homebrewers invented a new thing and called it that. Instead of a continuous flow of sparge water at a rate calibrated to match the runoff of wort, the sparge volume is divided into 3 or 4 batches each of which is run on all at once whenever the level nears the surface of the grain bed. Not only very easy, but it “works” the mash and gives better efficiency than continuous flow. Another example of Martin’s point that sparging is all sparging, just differing in how and when you add the water.)
I suppose the question of batch sparging, whether to stir or not, is a matter of personal preference. My intuition says stirring might gain me a couple of points more, but I really don’t know. Certainly not stirring so you don’t have to set the filter bed again is more convenient. However, sometimes when I stir in the sparge water, I find a couple of dough balls that I didn’t quite get crushed during the initial stir-in (particularly when using Maris Otter), so I know I am getting some more points. I usually let the stirred in sparge sit for 15 more minutes before finishing the lauter.