It seems that the common scheme for false bottoms is 3/32 hole diameter on 5/32 centres. It doesn't seem this ever gets challenged. Has anyone tried smaller/larger holes and found them to be better/worse? I'm about to invest in a large-ish one for a 30gal tun and want to make a good decision. I know the 3/32-5/32 pattern works - just looking to optimize a bit.
I've previously been batch sparging with a screen of appx. bazooka pattern, which has a smaller hole size. It doesn't get stuck sparges, but the runoff speed under gravity slows to a dribble for the last gallon that I need from the first runnings. Things are faster during the second runnings as the mash is hotter. Still, the last gallon or so takes as long as all the gallons before it.
I batch sparge, and do 16.5gal batches. Will likely have a fb of between 6 and 18'' diameter. The MT will be 18'' i.d., but I'm hoping to cut costs and go with a 12 or 6'' FB. The MT has a conical bottom with about a 15deg angle and a bulkhead in the centre of the bottom.
All experience/advice appreciated!