Author Topic: Stuck mash even with rice hulls, what did I do wrong?  (Read 732 times)

Offline Barelycapable

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Stuck mash even with rice hulls, what did I do wrong?
« on: June 19, 2022, 04:08:45 pm »
I'm currently brewing a Celis White clone for my dad for fathers' day, and the mash stuck like crazy and gave me a bunch of trouble.

Grain bill is: 47% belgian pilsen
43% white wheat malt
5% flaked wheat
5% carapils
And about 4 handfuls of rice hulls, more than I've ever used before

I'm brewing in an Anvil Foundry 10.5 gal and I've done about 6 brews in this thing before, using my LHBS grain mill crush. I've had a stuck sparge once before too with a mostly barley bill, also using rice hulls but less than I did today.

The mash today was absolutely, positively stuck. Literally just a trickle coming out of the false bottom. Like I said, used plenty of rice hulls and all of my grain was in ~5 gal of mash water.

I stirred like crazy, scraping the false bottom, which barely helped. I ended up dumping the mash and grain into a spare bucket, and transferred back into a nylon brew bag which worked fine for the rest of the mash.

RDWHAHB and all, but I'm going crazy trying to figure out what caused this. Am I missing something? Might my homebrew store's mill gap size be too small? Have I angered the beer gods with my arrogance?? Any advice would be greatly appreciated.

Offline dmtaylor

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #1 on: June 19, 2022, 10:12:12 pm »
Hmm. It is difficult to say exactly what is going on. What was your mash temperature? Did you undershoot or overshoot your temperature goal?  Did you add any acid?  Do you know the mash pH?  It is possible the LHBS has a tight mill gap, however it is very unlikely.  Perhaps you stirred too much. I think it is better to stir once in the beginning of the mash, and then leave it alone. This way, if a fine layer of proteins and starch forms on the surface of the mash, it can be lightly raked to allow improved flow through the top layer.  But if this is all stirred up immediately prior to runoff, well then you have less control.

Excellent first post. Welcome to the forum. I hope this sparks some useful ideas.
« Last Edit: June 19, 2022, 10:15:10 pm by dmtaylor »
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Offline BrewBama

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Stuck mash even with rice hulls, what did I do wrong?
« Reply #2 on: June 20, 2022, 07:13:04 am »
A few thoughts:

I have had stuck mashes before and it came down to a differential pressure above and below the false bottom. A manometer can be used to monitor this differential so actions can be taken prior to catastrophe.

The grain crush for the system, mash tun and false bottom design, and recirculating or drainage velocity can contribute to the problem. A course crush for problematic systems as well as a cpl pounds wet rice hulls and raking the grain bed can help.

I use BrewBags to control the grain bed. It’s important to note that there are some bags with a fine mesh that don’t do as well as others with a courser mesh. For example, my previous bag was fine and I would get a stuck mash from time to time but I replaced it with a bag designed for recirculating and I haven’t had any issues even with ‘sticky’ mashes.
« Last Edit: June 20, 2022, 08:30:08 am by BrewBama »

Offline KellerBrauer

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #3 on: June 20, 2022, 07:41:15 am »
I don’t know about the Anvil Foundry, but I can say that, in my experience, when you have as much wheat malt as is in this recipe, 3-4 handfuls of rice hulls is not nearly enough.  I would have used about 8 oz. min.  I recently brewed a Hefe and used a pound of hulls with 51% white wheat in the grain bill with no issues at all.
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Offline jeffy

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #4 on: June 20, 2022, 08:11:09 am »
I once had a stuck mash on a wheat beer because I put the rice hulls into the mash tun first right on top of the false bottom and then added the malt.  Since then I have always mixed the hulls in thoroughly before adding the grist into the tun.
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Offline denny

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #5 on: June 20, 2022, 08:45:31 am »
Did you try cutting the grain bed? The other thing to consider is that not all malt will act the same way. It seems like the moisture content of the particular bag can influence it. Just an observation based on experience.
« Last Edit: June 20, 2022, 08:47:10 am by denny »
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Offline majorvices

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #6 on: June 20, 2022, 10:02:47 am »
Nit picking, I know, but you had a stuck lauter, not a stuck mash. A stuck mash would be where you didn't see conversion.

You might try lining your MT with a fine micron brew bag like the ones used for BIAB. The false bottoms sometimes get clogged depending on the crush of your grain. The fine micron brew bags do an amazing job of keeping that lauter flowing.

You could also try a beta-glucan rest at about 131F for 15-30 minutes if the problem persists.

Offline hopfenundmalz

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #7 on: June 20, 2022, 10:25:35 am »
Nit picking, I know, but you had a stuck lauter, not a stuck mash. A stuck mash would be where you didn't see conversion.

You might try lining your MT with a fine micron brew bag like the ones used for BIAB. The false bottoms sometimes get clogged depending on the crush of your grain. The fine micron brew bags do an amazing job of keeping that lauter flowing.

You could also try a beta-glucan rest at about 131F for 15-30 minutes if the problem persists.
I think Randy Mosher recommended that for beers with a high % of unmalted wheat. It would help here too.
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Offline ynotbrusum

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #8 on: June 20, 2022, 10:29:53 am »
I have found that my Foundry works best with a 400 micron bag, whether recirculating or just mashing and stirring occasionally.  Also, if recirculating, let the mash sit for 10-15 minutes before starting the re-circ. and re-circ at barely over a trickle (I use a Loc-line halo-type manifold, rather than the recirc plate that came with the system). 

The geometry of the Foundry 5-gallon batch size  (the 10.5 gallon system) is pretty narrow and tall, so I will often stir once or twice during recirculation or even if just mashing, to keep it flowing well.  High wheat, oat, and similar sticky additions call for extra care, for sure, but don't be afraid to stir it up or add a bunch of rice hulls, if you have them on hand.  Also, I use the grain basket lined with the BIAB bag, then do my sparging in a couple large plastic buckets, adding most of the sparge water to the basket in the first bucket, then transferring to the second bucket for more sparging (gently pouring sparge water over the grain) and pouring wort back into the boil kettle from the first bucket to proceed to boil.  I then do the same transfer of the lined grain basket back to the first bucket and let the draining continue until it is complete.  I add that last drained wort to the boil kettle and proceed to boil it all - 30 minute boils seem to work fine FWIW.
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Offline Barelycapable

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #9 on: June 21, 2022, 10:38:22 am »
Hmm. It is difficult to say exactly what is going on. What was your mash temperature? Did you undershoot or overshoot your temperature goal?  Did you add any acid?  Do you know the mash pH?  It is possible the LHBS has a tight mill gap, however it is very unlikely.  Perhaps you stirred too much. I think it is better to stir once in the beginning of the mash, and then leave it alone. This way, if a fine layer of proteins and starch forms on the surface of the mash, it can be lightly raked to allow improved flow through the top layer.  But if this is all stirred up immediately prior to runoff, well then you have less control.

Excellent first post. Welcome to the forum. I hope this sparks some useful ideas.

Thank you, and everyone else, for your thoughtful responses! Really excited that my first post brought some replies. Lemme answer your questions 1 by 1:

1. Temp was bang-on (150F) throughout the mash, according to both my Foundry's internal thermometer and my Thermapen
2. Yes, pre-acidified with ~8ml lactic acid, but I did not break out the PH meter today, I normally only use that when I'm kettle souring.
3. Agreed re: LHBS crush, it seemed normal and I haven't had trouble with mostly barley grain bills that went through the same mill. Could've been adjusted I suppose, I'll talk to the employees next time I'm there.
4. Interesting technique with the mash stirring, I definitely stirred the s*** out of it nearly constantly in the hopes of unsticking it, I'll try your way next time.

I did end up using a brew bag, which worked great. I intend to do so for future wheat beers as well.

@majorservices, Ah gotcha! yes, conversion was fine, but the grain soaked up a lot of my water volume and no matter how much I squeezed the bag, I couldn't get to my target pre-boil volume. So, without thinking, I just topped off my kettle with more RO water, which tanked my OG by like 15 points.

Have not heard of a beta-glucan rest before, I'll look into it.

Thanks again, friends!

Offline denny

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #10 on: June 21, 2022, 11:40:19 am »
Itsbalwaysnangood idea to rinse hulls before using. You get some of the residual dust off of them, and they won't absorb as much of your mash water.
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Offline BrewBama

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Stuck mash even with rice hulls, what did I do wrong?
« Reply #11 on: June 21, 2022, 12:07:43 pm »
A few thoughts:

 … a cpl pounds wet rice hulls and raking the grain bed can help.



Offline ynotbrusum

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #12 on: June 21, 2022, 12:12:52 pm »
There are also products that help with viscosity issues in lautering.  I don't think I have the name handy, but it was something like "Visco Buster", which I presume is an enzyme enhancer of some sort.

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Offline denny

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #13 on: June 21, 2022, 12:32:41 pm »
A few thoughts:

 … a cpl pounds wet rice hulls and raking the grain bed can help.



Absolutely.  That's why I suggested cutting the grain, too. Just another word for raking.
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Offline fredthecat

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Re: Stuck mash even with rice hulls, what did I do wrong?
« Reply #14 on: June 21, 2022, 02:25:15 pm »
any thoughts on having a rectangle-shaped igloo cooler mash tun vs. the tall circular (gatorade containers?) cooler mash tuns re: stuck/very sticky mashes?