I built a recirculating coolant system for my 6 wheel Lortone arbor five years ago. I used a heavy 30 gallon plastic tub, smaller bucket, submersible pump, plastic tubing, valves and pvc piping. The pump is inside the bucket sunk into the 30 gallons of coolant. Coolant is sprayed up against the wheels through pvc piping and then collected into a drain system that allows the coolant to enter the bottom of the tub where dirt settles out of the coolant. With the pump inside the submerged bucket clean coolant enters the bucket over the top of the bucket and gets reused. I clean the sump out every six months and it all seems to work well. My wheels are diamond plated and resin wheels and so far have not worn out. I use them hard on both silver and lapidary material. I agree that just recirculating the same small amount of coolant inside the tray of an arbor would quickly wear out the wheels of an otherwise very good machine.