Give it a few days. Hopefully it'll clear up over night. I found that if you put some stuffing or filter floss in it, it clears up faster.
How long has it been like that?
Doing pwc will help out too, make sure you dont just dump it in becuase that will stir up more sand
What is pwc
I added sand but did not take all of my water out ad now I can't get the sand to settle
+1 good advice. I guess some aquarium salt does the job to? My neighbor told me to awhile back and it cleared up, coulda been the filter.