in the field I usually fill a 5 gallon bucket with 1/2 classified material, then I transfer to 1/4 inch and a 5 gallon bucket full of 1/2 in the area I prospect usually fills a 1.5 gallon bucket full of 1/4 inch. then I run this through the sluice. dump all my sluice/dredge/highbank/etc concentrates in a bucket and bring home. then those get classified down to 30 mesh and 50 mesh, each processed individually in the blue-bowl to grab that smaller gold! its small but it really adds up quick!
ive read that the best fine gold classifier recovery setup should be 30/50/70/100 meshes but past 50 is micron, but I've read that in this range most of the gold is in the 70 mesh range..... how they come up with that without knowing the area someone is prospecting, I have no clue so take that with a grain of salt! best of luck in your decision making!