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Rubbermaid MLT and SS braid

Quick question or two…

I have the 10gal Rubbermaid cooler for my MLT and have only done 3 batches with it. So far it has worked pretty well. My concern is that there is some pretty good warping going on on the sides. I have 2 bulges that are probably about 1/2 inch running vertically. Is this normal? When filling with 170F water is creeks a lot. Clearly the plastic is expanding.

Has anyone had the plastic crack or fail? I am wondering if the cooler was the way to go or not.

I also use a 20" piece of SS braid as the “filter”. I have it in a circle that is about 10" in diameter and goes to a T that is connected to the bulkhead. This worked great for the first 2 batches in it, but last weekend I basically got a stuck sparge. Raising the tubing and allowing wort to backflow a bit would fix it some and then it would slow again. I have 14ga copper coil inside so I know it isn’t collapsing. I did notice the braid had “shrunk” or gotten a bit compressed, so maybe that was it… just odd to get sticking with the braid. I am also wondering if my crush is to tight. I have the mill set at .032 as .039 seemed to let a lot of whole kernels to pass straight through.

Thanks for the help.


Are you sure you’re using a stainless braid and not one made from silvery plastic?

Def the SS braid… the wires are very sharp and it just barely clings to my rare earth magnet. I am sure it isn’t the plastic.

I am sure the copper coil I have inside it to prevent collapse got compressed or shrunk so the braid was super tight. Seems like a had a lot of flour from the crush as well.

I am mostly worried about the warping of the walls of the cooler.

Thanks for the help.


Your warping sounds pretty extreme, but as long as there aren’t any cracks you ought to be okay. My cooler started getting some ripples in it when I did a couple of overnight 160+F mashes but nothing that’s scary, at least so far.

If the braid is so tight that you’re clogging the entire length, you could stretch it out a little to open it back up.

Re: the stuck sparge problem…

I too have a cooler with an SS braid. After doing six or seven batches with no problems, I got two batches in a row with stuck sparges. The grains were all crushed on the same mill and the grain bills for the two stuck batches were nothing unusual.

The only variables that I could come up with are runoff speed and the cover on the MLT. I tried running off the two stuck batches faster than I had done previously because everything I read indicated that runoff speed was not a factor in batch sparging. I also recall that I put the cover of the MLT on during the runoff/sparge of the two stuck batches in an effort to avoid heat loss. I wonder if that caused some sort of suction problem that might have collapsed the braid.

In any case, for the four batches since those two, I rembered to run off farily slowly and I didn’t put the cover on during the runoff/sparge and I’ve had no problems

I’ve been mashing in a 10 gal Rubbermaid for years… there is some warping inside now, but that’s as far as it ever went.

Have you been putting boiling hot water into the tun? That is apparently beyond the temperature tolerance and seems to lead to warping and cracking.

The stuck sparge is much more apt to be due to the collapse of the grain bed than the collapse of the braid. Try malt conditioning or rice hulls.

The running speed has no effect on batch sparge efficiency, but it can lead to a collapse of the grain bed and a stuck sparge if the grain crush is fine and the husks are shredded, or if you use a lot of huskless or high glucan malts, like wheat, rye or oatmeal.

Runoff speed isn’t a factor in efficiency. You can runoff as fast as your system will allow…that’s the important part. If you don’t already, try starting the runoff slowly and then increasing the speed after the filter bed is established.

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