I just removed the regular gravel last week and replaced with fluorite. I used a square plastic container to slowly scoop out (most) of the gravel after removing about 2/3 of the water. After washing the fluorite, it was put back in with the same container. Lower the container full of gravel to the bottom of the tank and then dump very slowly. There was very little dust in the fluorite and the water cleared up quickly, but I do have a Fluval 305 and AC30 on this tank. I have about 20 fish in this tank ( stayed in during gravel change) and everyone is happy with the new gravel especially the cory doras... I still have one end of the tank to do on the next WC...
The next WC I used a large rubber hose with a one inch inside diameter to suck out the gravel. This worked great, but you need two people because a 5 gallon pail fills up really quick. The water in the old tank was hardly cloudy after removing the gravel.