Does Recirculating The Mash Cause Channelling?

[Jye]

Since I started recirculating the mash (this is only done at the end to clear the running) I have really noticed the brown sludge that forms on top of the grain bed and I think this may be causing channelling down the walls of the MLT. I initially though the channelling was caused by my SS braid, it used to only have 3 loops and sat against the wall where it would drain the wort. But today I looped it 4 times to bring it in away from the wall and I still got channelling.

This isnt a problem for me since I am batch sparging and still get very clear runnings. But could this be a problem if you recirculate all of the time since the wort would continually run down the walls and not through the mash?

Does this happen to anyone else?

Cheers
Jye

 

[Justin]

I haven't noticed any channelling as a result of recircing, but from your pictures-is that exactly how your grain bed is when recirculating? If so it looks like you could do with more water to be honest.

I always had an inch or so of water on top of the grain bed when I used to fly sparge and this does a great job of buffering the delivery of sparge water and makes it's placement less critical and also stops you from boring holes in the bed (I never went for the trinkety sparging sprinkle, they cool the water too much. I use a sparge ring very similar to yours and sit it on the grain bed under the water level). If that's all the water you have over your grain bed when your trying to recirc then I would add some more. The fine particles that settle on the top can sort of seal off the bed a little bit (especially obvious when you've got a really sticky mash), so they might be sealing off your bed a little and because you seem to have a domed shape in the middle it looks as though your sparge water is running down hill to the sides and draining that way. As I mentioned above, if you add more water to the grain bed so that it is always covered does it still do the same thing?

But as you said, your batch sparging so channeling is of no concern really, and your getting clear run off. The way I batch sparge is that I will add my first lot of water to the tun (usually around 7-10L) before stirring and letting it sit for 10mins (that raises the water level well above the grain bed). Then I'll throw the pump on and start clearing the wort before transferring to the kettle. I'll run it dry then pump in the secoond batch water, stir, sit, recirc and transfer.

So as long as it clears up there isn't really a worry anyway.

That's been my experience anyway.

Cheers, Justin

 

[Jye]

I haven't noticed any channelling as a result of recircing, but from your pictures-is that exactly how your grain bed is when recirculating? If so it looks like you could do with more water to be honest.

Thats a pic after draining the wort there is about 15cm of water above the grain bed and the recirculating ring sits a few cm under the water.

But as you said, your batch sparging so channeling is of no concern really, and your getting clear run off. The way I batch sparge is that I will add my first lot of water to the tun (usually around 7-10L) before stirring and letting it sit for 10mins (that raises the water level well above the grain bed). Then I'll throw the pump on and start clearing the wort before transferring to the kettle. I'll run it dry then pump in the secoond batch water, stir, sit, recirc and transfer.

So as long as it clears up there isn't really a worry anyway.

That's been my experience anyway.

Cheers, Justin

This is the same method I use with 2 equal run offs of 16L.

 

[AndrewQLD]

With batch sparging it is dependant on how FAST you drain the tun as to how much channeling you get, I have seen the same thing in my system if I drain too fast, the grist seems to collapse into the middle and pull away from the wall, not that it makes any difference and it never bothered me but I noticed it was an indication of an imminent stuck sparge with the mash ending up like a block of concrete in the bottom of the tun if allowed to continue draining at that speed.
That is how I see it in my system, but as all systems differ so do the methods of draining the tun.

Cheers
Andrew

 

[Screwtop]

Was having a similar problem Jye, looked almost identical. However I was using a round slotted copper manifold. Changed that to PVC pipe with holes and still had the problem. Changed to SS Braid and still the same. Opened my mill roller gap up to 40 and this improved, now 42 and much better. Seems the suspended flour settles last (as it would being the lightest particle) and covers the grain bed, this mud is quite impermiable. Wort finds a path of least resistance down the sides of the grain bed leaving a domed grain bed covered in mud.

 

[bindi]

Off topic <_< sorry. Screwtop post 666, oh no me also
I laughed when I read mud on top of your mash, it looks more like grey cement . 666

 

[vlbaby]

That a lot of mud jye. I usually only have a fraction of that amount on top of the mash, and I use a herms so the pump is running continously. I would think that your grains are crushed too fine.
With that said, I wouldnt be too concerned about it if its just recirc that your doing and the wort is coming out clear. But if its a herm/rims that your thinking of in the future then maybe it could be a problem. I suppose it could result in uneven heating of the mash.

cheers

vl.

 

[Tony]

I have had mashes form this "mud" on top of the grain bed too.

I tend ot get my mash paddle and break up the top couple of inches of the mash to keep it flowing through the grain and minimise chaneling during the mash.

I did one once and it forned a half inch wide crack in the grain bed thst all the wort was traveling down,

If i give it a light mix to keep it flowing during the mash it wont be clear but at the end i let it clear out before i send it to the kettle.

I dont recon its any big deal if your batch sparging anyway.

I used to be a fly sparger but switched when i noticed big time canyons sending plain sparge weater strait to the kettle.

here are some pics of my mash recirculating and the drained grain.

i get 75 to 80% efficiency.

cheers

 

[Kai]

...but I noticed it was an indication of an imminent stuck sparge with the mash ending up like a block of concrete in the bottom of the tun if allowed to continue draining at that speed.
That is how I see it in my system, but as all systems differ so do the methods of draining the tun.

If i drain my tun at max speed I suffer from exactly the same problem.

Jye, I would only worry about channelling if your efficiency has taken a hit since you started recirculating. If it has, then my personal preference would be to alter my manifold rather than drop the vorlauf step.

 

[poppa joe]

Since i cant find where to start a topic ....I AM GONNA ASK HERE>>>>
Seeing that we are talking about recirculating..
Will a pond pump handle the heat for recirculating ..from a Grant...
Scored an new ..el cheapo pond pump and wondered if it is an option.. :beerbang:
I have heard that some people use them.. <_<
Cheers
PJ

 

[homebrewworld.com]

Never had that mud, but i have had the mash ' squeeze in ' from the sides of the tun, on a fast sparge.
Never had chaneling or lumps/balls.
God Bless the RIMS,