17 replies to this topic

[beach]

I've been brewing AG for ~3-years now and switched from a rectagular cooler with a manifold to a keggle MLT about 1 1/2-years ago when my cooler cracked on the inside. I had an extra sanke keg and wanted to move up to 10 gallon batches anyway. I always had good luck lautering with the manifold but really didn't want to mess with building one for a keg. I (thought) I did a fair amount of research and planning prior to buying a false bottom for my new MLT build. I bought this one- https://www.homebrew...rts_p_1010.html , installed a ball valve and fabed a dip tube. I have to add 2 1/2 gallons of *foundation* water to make up for the space below the FB, but I vorlauf at least that much (manually, no pump in my brewery) prior to starting the sparge (I fly sparge via gravity using a Bilchman AutoSparge). I have learned how my system works and can get very clear run off.Here's my ish- as long as I hit my mash temp when I dough in, re: I don't have to add heat and stir the hell out of it to raise the grain bed temp, I nail my predicted OG with ~80 mash efficiency. The more I need to stir, the more fine malt particulate (flour, small pieces of malt) get through the FB and the lower my pre-boil gravity goes. I missed my mash temp by 4 degrees on Saturday and needed to add some heat. I use a 2000 watt heat stick and stir until it gets to temp. I was .04 below predicted boil gravity and 72% mash efficiency. In an effort to hit my perdicted OG (Beer Smith 2) I put this one together predicting 75% efficiency. When I clean out the MLT it's pretty predictable that the more I stirred, the more crap there is below the FB. Could it be that the *fines* create a malt mud below the FB where I can't get to it to get it re-suspended with the rest of the grist in the mash and the emzymes can't get to it to efficienctly convert it to sugars and sparge water can't rinse the sugars out? I have been checking pre-boil gravity on a regular basis and when I'm low I end up running more wort into the BK and extend the boil to get to where I want to be. This leads to long brew days and lots of LP burned in the process.I've backed off my mill settings so I have a coarser crush. I almost built a manifold yesterday but decided to seek advice from the massive BB's brain trust. Any sugestions?Beach

Edited by beach, 23 April 2012 - 07:53 AM.

[SchwanzBrewer]

Sounds like you need to get a pump and recirc prior to sparging to clear the wort and make sure there isn't anything building up below the false bottom if i read you right.

[Genesee Ted]

Sounds like you need to get a pump and recirc prior to sparging to clear the wort and make sure there isn't anything building up below the false bottom if i read you right.

This is my thought as well.

[Dave McG]

I'm thinking it's the support grid. It looks like whatever square has the drain would flow the best, and those further away from the drain would see some amount of restriction.On a good mash, the grain stops most convection, which would be the main driving force for natural mixing. The foundation water under the bottom remains mostly water. When you drain, the one square of water drains, then after that whatever sees less restriction. Wort has gravity pushing it down, but the water in the squares far from the drain see restriction. Wort wins.When you stir, you first do an effective dilution by mixing in the water that was out of play. Then, you drain and some good wort is now in the poor flow areas.I know there is space below the grid where everything can flow freely, so flows aren't stopping, but they are seeing restrictions that don't effect things evenly.That's my guess.

[beach]

Schwantz, doobah and Dave, thanks for the replies. Not really sure what I should do about my issue, but I certainly appreciate the time you took to consider my problem and respond.Beach

[BlKtRe]

A couple of things. You must be super careful using a pump with a FB in a MT. The risk of sticking goes up significantly since the pump can and will compact the grain bed. Thats why people use a grant after the MT and pump from the grant.Im not sure if your FB is flexing or not as Dave hinted about. I expect some particles to get through any type of filtering device until the bed becomes its own filter after vorlauf. Your problem is typical. If it was my setup I would buy bulk rice hulls and place those on top of the FB making a decent layer to act as a filter. When mashing in dont stir into to the rice hulls but rather the grist on top. Call it a good day after that.Edit: Im guessing the holes in the FB are the correct size and spacing?

Edited by BlKtRe, 24 April 2012 - 06:26 AM.

[No Party JKor]

Getting 72% efficiency when you're aiming for 75% is pretty much with the margin of error. I'd call that hitting your number. If it was 65% it would raise a red flag for me. +/- 3-5% is fairly normal batch-to-batch variation, IMO. Unless you are hitting EXACTLY 80% every time when you don't stir. Based on what you've said I'd need more convincing to believe this issue is related to stirring. I doubt any extra grain matter getting through the FB is causing any noticeable conversion issues. Maybe next time you hit your temperature try stirring for a few minutes, as a control, to see if the trend continues.

[BlKtRe]

Ever notice any dough balls when emptying the tun? Are you adding grist to water or the other way around?Im also not buying into grains not converting that are getting under your FB.

[Mya]

Ever notice any dough balls when emptying the tun? Are you adding grist to water or the other way around?Im also not buying into grains not converting that are getting under your FB.

I would think some of the heaviest concentrations might be stratifying below the FB pick-up, and no t making into the kettle, if anything, leery of a domed bottom mash tun myself

[beach]

A couple of things. You must be super careful using a pump with a FB in a MT. The risk of sticking goes up significantly since the pump can and will compact the grain bed. Thats why people use a grant after the MT and pump from the grant.Im not sure if your FB is flexing or not as Dave hinted about. I expect some particles to get through any type of filtering device until the bed becomes its own filter after vorlauf. Your problem is typical. If it was my setup I would buy bulk rice hulls and place those on top of the FB making a decent layer to act as a filter. When mashing in dont stir into to the rice hulls but rather the grist on top. Call it a good day after that.Edit: Im guessing the holes in the FB are the correct size and spacing?

My FB is very rigid so I don't see flexing as much of an issue and I'm glad to hear my problem is fairly typical. I have a shit load of rice hulls so trying that is easy. In my limited experience the holes (slots actually) look like others I've seen. The seller notes 16% open area.

Getting 72% efficiency when you're aiming for 75% is pretty much with the margin of error. I'd call that hitting your number. If it was 65% it would raise a red flag for me. +/- 3-5% is fairly normal batch-to-batch variation, IMO. Unless you are hitting EXACTLY 80% every time when you don't stir.Based on what you've said I'd need more convincing to believe this issue is related to stirring. I doubt any extra grain matter getting through the FB is causing any noticeable conversion issues. Maybe next time you hit your temperature try stirring for a few minutes, as a control, to see if the trend continues.

No, my efficiency varies a point or two either way on most batches. I had been running in the low 80% range for quite a while and then, with no changes to speak of other than stirring excessively, I landed in the low 70%'s. Lots of malt mud below the FB with those batches. I'll try a control experiment the next time I hit my mash temp.

Ever notice any dough balls when emptying the tun? Are you adding grist to water or the other way around?Im also not buying into grains not converting that are getting under your FB.

No dough balls that I've seen. I underlet the liquor into the tun and add grist to liquor.Beach

Edited by beach, 24 April 2012 - 08:57 AM.

[beach]

I would think some of the heaviest concentrations might be stratifying below the FB pick-up, and no t making into the kettle, if anything, leery of a domed bottom mash tun myself

I'm picking up mash liquior about 3/4" from the bottom of the keg. On a water only run I have about a quart of dead space in the MLT.Beach

[SchwanzBrewer]

Hows your water? Do you control it or just go with whats available? My efficiency went up when I started controlling my water quality. The forum tended to agree that it resulted in the proper PH and full conversion. Just another place to look.I can't imagine not stirring in the mash really well. 1. It's one of my favorite parts of the brew day. 2. I can really make sure I get all the dough balls out. 3. It ensures proper hydration of the malts giving them ample conversion time and not spending time hydrating first.Cheers,Rich

[beach]

I've got a pretty good grip on my water. Wards report, 50/50 diution with RO (for most styles) and add salts and acid to reach a profile and pH. Using Bru'n Water I hit mash pH dead on most of the time. I stir like hell for pretty much the same reasons you do Schwantz, other than I will say that I'm not overly fond of it.Beach

[Mya]

so don't stir so violently? vigorous doesn't mean beat like a rented mule

[beach]

I don't rent mules, I beat the shit out of my own. :blush:Beach

[Mya]

I don't rent mules, I beat the shit out of my own. :blush:Beach

LOL

[Dave McG]

I'm still thinking it's the pretty unique support grid under the FB. When I followed the links you gave about the specific false bottom you have and looked at the extra photos the showed, the first thing that came to mind was the type of baffles put into tanks to prevent sloshing.

[beach]

The bottom of the supports are about 1 1/2" above the bottom of the keg.Beach