new MLT won't clear the wort during recirculation

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nolasuperbass

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About a year ago, I upgraded from my cooler MLT that I'd had forever to a traditional keggle-style MTL. Previously, when recirculating with the cooler MLT, I would use my chugger pump for about 15 minutes. The wort would be crystal clear going into the boil kettle. At the time, I never used gelatin or whirfloc, and the beer always had great clarity.

For some reason, I just can't get the wort this clear during the recirculation with the new MLT. The pump, even with the ball valve on the output cranked down, would cause severe channeling, the wort would never clear, and my efficiency would suck. I finally figured out that the pump was just too much, and I started manually recirculating with just a trickle coming out. That fixed the efficiency, but it's a PITTA, and the wort is still not as clear as it used to be. The resulting beer needs about a month of lagering before it will completely clear up, and that's even with both gelatin and whirfloc. The mash never sticks (knock wood), and rice hulls don't seem to do anything.

Clearly, there's something about the physics of this that I don't understand. The new MLT has a much bigger screen in it, so there should be less of an issue with channeling with any given amount of grain, right? I was considering wrapping the false bottom in a paint strainer bag, just to give it a little more filtering power, but, for all I know, restricting the flow may make it worse. I was hoping that maybe the engineers on here would have some insight. Thanks in advance.
 
Maybe you have a to big surface for the grist leaving you with a thin maltbed?
 
Are you using a false bottom? I use a RipTide pump at full throttle during 100% of the mash and have zero channeling issues. The wort comes out clear as well.
 
It is a standard SS MLT with a false bottom. I think that I got it from Brew International. I only brew 10 gallon batches, so there's always 20 or more pounds of grain in it. That makes it most of the way full, and provides a deep grain bed.

How clear are you getting the wort with your RipTide as it's going into the kettle: super, finished beer clear, or sort-of clear?
 
The wort is really clear, both in the mash tun (being recirculated on top of the grain bed) and when transferring to the BK. I'm using a Blichmann 20 gallon kettle for a mash tun with their false bottom. I almost always do 10 gallon batches and run my pumps for minimum of 70 minutes including mash out. When I transfer the wort to the BK I throttle the pumps down to a trickle.

I have been grinding my grains at .035" the last few brews.
 
My last two systems (all keggles) have used this false bottom from morebeer. They work perfectly in a sanke keg. Recirculating wort in the MLT has always cleared perfectly and quickly. I use a chugger at full flow. No bags or whatever. What you see is what I heat the strike water and mash in with. I keep about an inch or two of fluid above the grain and the silicone return and sparge tube simply lays on top of the grain bed causing a swirling motion of the liquid.

https://www.morebeer.com/products/false-bottom-stainless-steel-domed-12-diameter.html

20171214_213404.jpg
 
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With a tall grain bed. I'll bet your false bottom is collapsing. Pumps can create a ton vacuum force then add in the weight of the grain a thin false bottom doesn't stand a chance. I've seen pictures of some heavy duty false bottoms completely flattened from the vacuum created by a pump.

Will the wort run clear if you vorlauf some off by hand? If it does it's for sure the vacuum collapsing your false bottom.
 
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