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.