Just want to clarify a couple things - This fluid bed sluice is completely different than either the original Schmidt design or the Bazooka Gold Trap. Both of these designs are a "closed system", i.e. water is captured underneath the tray and is used to provide water to the tubes - any water not used to fill the tubes is retained in the machine.
The Aurora Mining Products fluid sluice is an open system. Water flows down the plenums (the vents on each side) and enters the fluid bed through the holes. The angle of the plenums is very important because it allows the pressure and flow to be even in each hole. Any water not used in the fluidization exits the rear of the machine (for clarification the front of machine is flare side). This system creates a superior water flow and maintains a constant water pressure. This means material is processed quickly and evenly throughout the box without build-up. This also keeps the bed liquefied. Incoming material is instantly flattened out allowing heavy materials to work their way to the bottom of the tray. Waste material is flushed from the machine after new material is deposited.
I believe classifying material is vitally important to gold recovery, especially fine gold. One of the most important features of this machine is the ability to slow the water entering the material tray without sacrificing material processing in the fluid bed - The vents are not affected by changes in the water speed at the front of the machine. I classify my material to target the size of the gold I am attempting to recover then slow the water speed down on the material tray to process the material - about 1 second from drop to entering the machine at the grizzly. I use a rock placed upstream of the machine to regulate the water speed which creates very precise flows. All material will enter the machine in the first two or three rows of holes. This means material is staying on the material tray and is not being suspended in the flow. Gold recovery (especially fine gold) is dramatically improved. This is all done while having the ability to process a 2 gallon bucket in 42 seconds! (see old Expedition sluice video
http://www.auroraminingproducts.com/images/products/videos/AMP_OldVideo.mp4). When I say the machines can easily process 4-5 buckets per hour (Recon) and 8-10 buckets per hour (Expedition) the only limitation is the digging and classification of buckets. As I stated I believe classification is very important in maximizing gold recovery.
The best part is that the Recon is only 18" long, weighs just over 2 pounds and fits in a backpack or 5 gal bucket. The Expedition is just under 24 inches and weighs about 4 pounds. These machines are lightweight, compact and get the job done.
Bottom line: This machine has been scientifically and mathematically designed to quickly process material which very high recovery rates, including fines and flour gold.