False Bottom Too False..

I have a 15 gallon Mega Pot and flase bottom from northern brewer. I have used it two times on my new setup that I just built and both times I am getting lots of grain, either through the screen or around the edges. I would say there is about a 1/4 of an inch, more likely a 1/8 of an inch where the false bottom does not meet the sides of the pot. Have any of you experienced this and have any idea how to prevent it? I use a pump so there is much more suction as opposed to gravity. When the mashtun is starting to get empty, it sucks up all the grain on the bottom and it gets into the boil kettle. I dont know if this will affect flavor, as I made a hefe two weeks ago, I have sampled it already, and I could not pick up off flavors.

I made an IPA this weekend and had the same issue. Should I just scale up my batches by a 1/2 gallon or gallon and account for this loss as dead space in the mashtun? Or, Should I even have this issue with the false bottom? Any advice would be appreciated.

Perhaps try some weather stripping around the FB? It might be just the right amount to close the gap and may act like a gasket once some grist is set on top of it.

Have you tried taking a half to full gallon out OG your mash and pouring it back over the top of the grain bed. This always helps me get a cleaner run off. The grain bed should settle a little more for you this way.

forsaken541 said:

Have you tried taking a half to full gallon out OG your mash and pouring it back over the top of the grain bed. This always helps me get a cleaner run off. The grain bed should settle a little more for you this way.

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This is the Vorlauf step, and is crucial to getting clear sweet wort runnings. It takes a few minutes to get it to run clear, but when it does, just move the pump outlet from the mash tun to the BK and you'll be good to go.

how fine are you grinding your grain? maybe grind coarser, so you have larger chunks in there; and/or add some rice hulls.

I do recirculate/Vorluof until the wort is clear, it takes a few minutes. I the start pumping the wort to the boil kettle, towards the end of the transfer I get a lot of grain coming through the tubing to the kettle. I like the weatherstriping idea, or some kind of rubber seal around the ourside of the false bottom. I might try to find something for that. I havent tried rice hulls on my new system, I could try that as well. I dont think it is a crush issue, i just think it is getting through around the edges.

Try using some High-Temp Silicone hose as your seal, just slice it down the length of it and slip it around your FB. I wouldn't use anything not food rated like weatherstripping because you never know what may leach out.

MyNameIsPaul said:

Try using some High-Temp Silicone hose as your seal, just slice it down the length of it and slip it around your FB. I wouldn't use anything not food rated like weatherstripping because you never know what may leach out.

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Excellent idea, Thanks!!

if it sits flat on bottom the edge would not be problem

High temp silicone hose as a gasket sounds like a winner.
Rice hulls will improve the flow which might reduce the vacuum the pump is
drawing below the false bottom. I use rice hulls and like them.
A looser mash might help.
Slowing down your pump flow would probably fix the problem independent of the other options.
Once the pump starts pulling faster than gravity, you are probably exceeding
the design parameters of the false bottom.

I would be interested in knowing how the problem is finally resolved
if you don't mind updating this thread.

Bob

LKHA: It sits off the bottom of the tun by about 3 inches.

Bob:
I tried the high temp hosing, at least what I had on hand, and that did not work, it was too thick. I just brewed 10 gallons of Pliney the Toddler and I coursed up my gind a little bit and added rice hulls. Also I increased the recipe size a little bit to account for ths issue, so I leave about a half a gallon in the tun, that way I do not suck up any of the grain material.

Also, I can only control the outflow from the pump to the boil kettle. I guess I could restrick the flow into the pump from the tun ball valve, but I thought that would be bad for the pump. Does anyone do that?? or is that a bad thing?

dixosx said:

Also, I can only control the outflow from the pump to the boil kettle. I guess I could restrick the flow into the pump from the tun ball valve, but I thought that would be bad for the pump. Does anyone do that?? or is that a bad thing?

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Never restrict the input of a March (or similar type) pump. It's not self-priming and needs to be "wet" at all times. You control the output with the valve. My guess would be that your system just needs a lot of vorlaufing to clear it up. May be time to switch FB's or build a manifold.

dixosx said:

... Also I increased the recipe size a little bit to account for ths issue, so I leave about a half a gallon in the tun, that way I do not suck up any of the grain material.

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Sounds like a reasonable fix. Depending on how you sparge,
the lost wort should be pretty thin.