Preventing a stuck mash

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davew
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Preventing a stuck mash

Post by davew » Wed Nov 30, 2016 11:14 pm

Last time I ran my RIMS system I got a stuck mash and my inner basket filled up and emptied the outer pot. What's the best way to try an prevent this?

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Re: Preventing a stuck mash

Post by BenB » Thu Dec 01, 2016 9:10 am

Are you using pre-crushed or crushing your own? Can you add some rice hulls?

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Kev888
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Re: Preventing a stuck mash

Post by Kev888 » Thu Dec 01, 2016 11:10 am

Reducing speed of recirculation can reduce compaction of the mash bed, it can also help to build to the desired speed gradually and to avoid too much depth/weight of wort building above the grain. Too fine a crush and/or too much stirring of the grain can liberate finer clogging flour, and with high percentages of stubborn grains (like wheat) rice hulls or oat husks (etc) may help, as Ben suggested.

But whatever you do there will be limits; some systems (and grains) are more free-draining than others. Systems such as the Grainfather have a central overflow so that the element and pump remain flooded even if the recirculation through the grain does clogg. The Braumeister design means that clogging can't cause the inner pipe to take up more wort.
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Re: Preventing a stuck mash

Post by Jocky » Fri Dec 02, 2016 11:47 am

Avoid suction on the mash tun caused by a siphon effect.

I kept getting stuck mashes, when running a length of hose from the tap on my MT bottom drain. The hose dropped down to a collection bucket or sometimes a pump that I'd use to recirc. What I hadn't realised was that the drop on the hose was causing suction on the grain bed.

The moment I changed to having the end of the hose above the bottom of the mash grain bed (meaning liquid was running out under gravity only) all my mash problems stopped.

If you need to run a pump off this then you want to run off into a lauter grant that is used as a reservoir for the pump inlet.
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Re: Preventing a stuck mash

Post by Troutman47 » Mon Apr 03, 2017 1:20 pm

Glad I came across this post, I've been having terrible trouble recirculating with my HERMS.

2 brews ago I used a lot of crystal rye so I put in some rice hulls and the circulation was much better, Sunday my brew was all pale malt and terrible circulation again, I gave it a stir and the grain bed was compacted on the false bottom, in desperation I got the bag of rice hulls out and chucked a load in, gave it a stir and circulation was fine again!

So I've concluded I need to put in 1-2% rice hulls in every brew from now on!

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Re: Preventing a stuck mash

Post by TheSumOfAllBeers » Mon Apr 03, 2017 1:23 pm

You could use a mash bag. A but like a voile bag that BIABers use, except designed to fit mash tuns. You can just lift the bag for easy agitation then

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Re: Preventing a stuck mash

Post by Fil » Wed Apr 05, 2017 8:25 am

also when starting the recirculation start slow and build up to the optimum flow rate, just the same as gravity draining the tun, if you open the valve slowly to full it works fine but if rushed straight to open gravity can pull the grains down with the liquor.
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Re: Preventing a stuck mash

Post by orlando » Wed Apr 05, 2017 10:47 am

You don't mention liquour to grain ratio, this can make a difference too. Slightly looser and crucially keeping the grain bed "floating". This requires a good inch or so of sparge water above the grain. I concur with the comments on pumps starting and running slowly is probably the most important, with husks if you are using a particularly high beta glucan adjunct.
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Re: Preventing a stuck mash

Post by johnmac » Sat Mar 17, 2018 9:23 pm

Running a chugger pump, 60L tun with perforated false bottom, 11kg grain / 30+ litres water. I've so far had it fairly well throttled back and no problems. However, it takes quite a while to pump out into the boiler. Dare I consider working up to full flow or is that idea asking for a stuck mash?

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Re: Preventing a stuck mash

Post by orlando » Sun Mar 18, 2018 9:14 am

johnmac wrote:
Sat Mar 17, 2018 9:23 pm
Dare I consider working up to full flow or is that idea asking for a stuck mash?
It's better to run the pumps gently whether recirculating the mash or sparging. If it is a full volume mash then you could try turning up the wick and see what happens but as you do the pump will suck down the floating bed risking a stuck mash.
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