[Depends what kind of sand it is and how fine and silty it is.
I regret not rinsing my southdown, and acually did end up rinsing it after the tank was setup, by means of filling and emptying the tank with fresh water about 6-8 times, stirring the sand as it drained. My sidewalk in front of my house is now stained white with araganite lol
My 75 I setup with silica sand, which isnt as fine as southdown. This I did not rinse, and it was clear in a week.]