Sorry to butt in on all the innovation goin' on around here, but I want to ask some really base questions about grain crush size and recirculation speed.
Did the second brew on the new rig today, and was less than pleased with some of the antics that went on. On the commissioning brew, I had a slight problem with the grain bed lifting when I changed from recirculate to lauter/sparge settings. When the vacuum momentarily stopped, the grain bed sprang up in the tun and released a lot of what appeared to be trapped air. I occasionally had this problem on the old rig, and it was not a major drama, exceptfor the very small amout of bits of grain that ended up in the kettle.
So, thinking about the issue, i came to the conclusion it was connected to my rather coarse crush of 1.6mm, as reccomended by mashmaster. Righto then. I'll pull the rollers in a bit to 1.2mm and crush it a bit finer and see what happens.
Well, what happens is that you get a grain bed set like concrete and a stalled pump. This occurred during ramp from 52 to 62 and in the ramp to 68. I thought I really stuffed it when the breaker tripped and the HLT/Boil side of my rig shut down, but that turned out to be an amateur gardener cutting through the cord of the electric hedge trimmer, with the electric hedge trimmer. Oh how we larfed!
Anyway, with power restored, and a couple of big handfulls of rice hulls in the mash, the problem went away, got beautiful clear wort and big fvck off channels during the lauter & fly sparge. Efficiency was well down too, which I'll put down to the channeling. I've never had channelling in my rig prior to adjusting the grain crush.
I have often heard tell of people crushing to "The Thickess of a Credit Card" which by my verniers and credit card is 0.9mm.
How the hell are these people not getting stuck mashes? Admittedly I don't have the best control of my recirc pump at the moment, but if you cant recirc faster than a Little Brown Pump, why bother spending the dosh on a very nice looking and superb quality Ultimiser pump from a well known site sponsor and contributor and building a special vessel with a custom made element to house one of the same bloke's very nice HERMS coils?
So, how fast do you recirc. and how fine do you crush? In the short term, I'll open the gap out to 1.4 and trial it again with a bag of rice hulls handy, but I'd still be interested in hearing what you're all doing.
Cheers!
FB