This is my 2nd run at using a dome style false bottom in my setup. Not the 2nd time ever, but the 2nd time I’m working with it in my system. I gave up on my last one after several stuck sparges which came about because that false bottom would float on me and the way the edges were designed it was easy for grain to get underneath and clog it up.
I just bought myself a new 7 gal cooler mashtun from Northern Brewer and it came with a 9 in dome style false bottom. It has flat edges all the way around so it sits flush on the bottom of the mashtun. They said it’s been trial tested and it’s desinged to work great yada yada. Well, first time using it today every thing went great with my brewday (the main reason I got the new cooler was to hold temps better which it did wonderfully)…going great until I hit time to collect the 1st runnings. Vorlauf went well and then the flow slowed, and then slowed some more and came to a hault several time. Dejavu for me. What a PITA to dump out the mash with half the wort in it I needed to collect into my kettle. I hooked up my old trusty bazooka screen in place of the false bottom but it wasn’t much better for the sparge but in the end I got my boil volume and on with my brew day.
My question is whats some tricks to a happy relationship with a false bottom of this setup. Are rice hulls really the key? How much should I use? Can I get away with rice hulls and still use a fine crush for better effeciency or is the crush going to kill my use of a false bottom? I don’t have my own mill, but I did ask the LHBS to crush my grains twice because my effeciency dropped from 75% to 65 or so when I started buying from him and before today the crush didnt’ seem like it was enough, there was lots of visible grains fully intact. So perhaps my crush did me in today but I’ve also had bad luck in the past.
For the record, I’m not talking a cush like flour but after milling twice there was lots of small bits and pieces but the hulls were not neccessarily “shredded”. My overall effeciency was back up to 75% and for the first time in a long time I hit my OG perfectly at the end of the boil.
So rice hulls it is?
Maybe I also need to run offer slower, somthing I’m not used to with my bazooka screen. I like the idea of the false bottom because it’s almost permenant, it’s durable…I just need it to be reliable.
How fast are you pulling the runnings? One possible issue could be pulling two fast causing the wort under the dome to dry up before it can be replaced with wort from above. This can cause compaction and also cause the syphon to be broken.
How fast…hard to say. I tried going about 3/4 valve open. I also had it wide open for a short while. I can see what you posted being the case. That makes sense and something Im not used to. Im used to a smooth rather quick flow with my bazooka screen. I guess ill try much slower next time. It will take me longer but slow flow is better than no flow. The flow was very broken. It would flow then stop and I could see gaps in the wort comming down the tube into the kettle.
Edit*…This batch also had a 1/5 lb of Flaked Barley…would that cause some lauter problems like Wheat and Rye?
I’d start slow and creep it up as it goes along. That amount of flaked should cause any issues.
Edit, what does the underside of the fitting that goes into the dome look like? Is it a street elbow or one of those cool elbow that is modified to look like a rook? If it is a normal elbow or street elbow, pulling too fast could cause it to suction to the bottom. I know this happens with pumps, not sure about gravity.
Steve its one of the newer styles like you describe. It has cuttouts all around it and sits flat on the bottom of the cooler to support the center of the dome.
No I went straight to draining the mash to get the 1st runnings in the kettle. I thought about doing a mashout as I typcially have done so in the past. Didnt this time though. Mash temp was probably down to 150* by this time.
Try adding water next time before pulling your first runnings. Most say that batch sparging works best when the runnings are equal. I don’t know how true that is, but I do like to get the thickness up to about 2qt/lb before first runnings.
Thanks for the tips. Everything you have said would help make a difference. I think it was probably a mix of things today. Too fast a runoff, thick mash. Some rice hulls and a mashout would surely help as well. I think we have it narrowed down. Ill be brewing again a couple weeks. An English Bitter…we will give it another shot.
It sounds like I have a similar set up. I use no less than 1.5 qt per pound and open the valve as little as possible for the vorlauf and first couple minutes of the runnins then let it rip and repeat with sparge. It sounds like you have a similar crush and I have no problems.
Open your valve just a tad at first until you are sure the grain bed has properly set. This will reduce the chances of a stuck sparge. A proper mash-out can also do wonders for your efficiency as well as for reducing the viscosity of your mash making it easier for the lautering. If you do decide to perform a mash-out, just be sure to give the mash 10-15 minutes or so to settle out after adding your additional water. This also allows more sugars to dissolve into the wort.
I have used a domed false bottom for almost as long as I have brewed. I have never used rice hulls. The only time that I have experienced a stuck mash was when I crushed my malt too fine. A false bottom requires a mill gap of approximately .040" when using a two-roller mill. Additionally, it is easy to compact a mash by running it off faster than liquid can flow through the bed, especially if the runoff rate results in a vacuum being pulled.
I will try going much slower on my next batch. That was probably the biggest culprit. The mash may have been a little thick, so slightly thinner may work better for me or at least throw in a mash out to get the grain bed warmer. I don’t know what the gap was set for on the mill at the LHBS, but in beers past I seen a lot (well, quite a bit) of uncrushed grains and my effeciency varied from low to mid 60’s. I felt that was too low and wanted it closer to 70-75% like I’m used to. I take a better look at the crush next time, maybe it is a bit too fine.
The gap is important with a 2-roller mill because roller spacing much closer than 0.040" results in substantial husk damage. I have used perforated and slotted false bottoms. I currently use a 9" Adventures in Homebrewing’s slotted dome in an 5-gallon industrial Igloo beverage cooler for my mash/lauter tun (9" Stainless Steel Domed False Bottom). A slotted false bottom is less likely to clog than a perforated false bottom.
That is quite purdy. Here’s what mine looks like. When I dumped the mash, It didn’t look like grains getting under the false bottom was a problem, which was the case with my old false bottome. This one sits nice and flush on the bottom of the cooler.
It may be an optical illusion, but the holes in that false bottom appear to be designed to clog. What is the diameter of the holes? With round holes, the hole size has to be large enough to allow unrestricted flow, but small enough that husk ends cannot fit into the holes. The beauty of slots is that they are more difficult to clog. Professional lauter tuns have slotted false bottoms.
