Unless you are very very patient, and have tons of time, forget about getting fluorite to be completely clean. What I do is take 1-2 cups of fluorite, rinse it once or twice like you would with normal gravel (in a bucket with running water, swirling and draining), then dump it into the tank. Once you are done, get a flat dish (glass, plastic, whatever) and fill your tank directing the water onto the dish. The dish should be large enough to help spread the water out and thus reducing the amount of force from falling water. After the tank is filled, leave it for a day or two for the dust to settle. Fill your mechanical filters with floss and run those for a few days till your tank has settled a bit more.
HTH
-Richer