so its not channeling... but what

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Southern_Junior

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so i currently use a 10 gal spike kettle with a domed false bottom. i had spike add a custom coupler at the top. i installed a blichmann autosparge. what i have noticed is that i get all my grain forming a giant almost whirlpooled mound in the center of the kettle.

on top of that, ive been having a really quick sparge... like 20 minutes. is my autosparge tube too long?
 
The domed false bottoms I've seen are only domed a couple of inches high at the center. Is the top of the grain mounded even higher than what the dome would account for?

Flow through a mash bed is the same as flow through soil. In soil testing we use rubber-walled cylinders that contain the soil mass and reduce the short-circuiting along the edges of the soil mass. If the walls surrounding the soil mass are rigid (like the metal side walls of the kettle, the liquid will preferentially flow along the soil/wall interface. This will also be the case in the mash tun.

If the grain bed depth along the kettle walls is shallower due to the mounding of the grain, then the combination of preferential flow path that is even shorter will mean that the short-circuiting will be more profound. If anything, flattening out the top of the grain bed in the kettle will help lengthen the flow path at the kettle walls and reduce short-circuiting.
 
Not sure if it will help in your system, but i double batch sparge and stir the daylight out of it each time. Im convinced it help rinse the sugars off the grain better than just dumping water in amd draining. May e you already do this. Just thought id mention it.
 
Probably the sparge arm is dropping water preferentially on the edges of the grain. Slow the sparge down, and maybe protect the top of the grain bed with foil with holes in or a saucer or similar.

I sparge via a silicone pipe laid on top of a plastic bowl lid (looks like a saucer) that I rest on the grain bed - this prevents any grain from being washed around. It's an idea I saw on here somewhere, so thanks to whoever that was.
 
What are you using for the actual sparge arm? The autosparge is just a valve the regulates flow through a tube. If you are just using that alone, all the sparge water would be entering the kettle at one point, at and angle, and creating a whirlpool.
 
Blichman claims the tubing alone makes the sparge water "gently rotate on top of the grainbed". Too fast a flow + "gently rotates" = whirlpool.

So, you can slow WAY down so that gentle rotation isn't moving the grain bed or rig up a sparge arm that with multiple drip points that don't cause rotation. You are going to want to slow down anyway, so you should try that first.
 
back when i was operating purely on gravity this wasnt a problem. i think i may just have been far to cautious of burning up my new pump. any tips on fly sparging with a pump?
 
I am having this same problem, so rather than create a new thread, I will try to get this one going again.

I am having trouble hitting my OG with the Blichmann AutoSparge. I have noticed that both during mash (I have Tower of Power) and sparge, there is a whirlpool action that promotes channeling down the sides of the grain bed. My first runnings are providing good specific gravity readings, but my final OG is consistently low and I'm only averaging a mash efficiency of 60-63% when channeling occurs.

Does anyone know if the amount of water above the grain bed will impact channeling. The last couple of brews, I noticed that I did not set my AutoSparge level correctly and ended up with >2" of water above grain bed. The channeling problem seems to be amplified when I leave too much water above the grain bed.

I really wish Blichmann would offer a better engineered sparge arm solution.

I slow my recirculation down as low as possible before it stops, but i still seem to get channeling.
 
If the flow is high enough to exhibit vortexing, then you need to reduce the flow. There is no reason to move wort that quickly through the bed.

Another thing that you can have is a schmutzdecke (aka: dirty layer) that builds up on top of the mash bed. That is one reason that some brewers slice their bed with a knife before runoff. I don't think that the knife trick is the way to go, but stopping the flow and gently raking the surface of the bed can help 'distribute' the schmutz and break it up so that wort can flow around it. Digging an inch or so into the bed and churning it slightly should do the trick. Of course, you might have to recirculate a bit to clear the wort. But it shouldn't be too bad since most of the bed is intact.

I always keep an inch or two of wort over the bed and use a downlet pipe for the wort return. A sparge arm is a waste of money.
 
Thanks for feedback. I am trying to slow the flow as low as possible without flow stopping altogether if I throttle flow enough, recirculation just stops.

I do notice that if I pick up rubber hose and move it around top of grain bed, this reduces channeling problem. I was hoping this would not be necessary. Perhaps instead, I should rake grain bed 2-3 times during recirculation?
 
I avoid disturbing the grain bed while the system is flowing. It's probably not a big deal if you are just raking the top of the bed though.
 
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