If it's the sand, then water clarifier won't help. Your best bet is to run some sort of mechanical filtration (even a cheap HOB filter) and change the filter pads often (you can just rinse them off and reuse them). That will pull a lot of the suspended particles out of the water column. Was the tank just set up recently? It's common when a new tank is set up for it to be cloudy for about a week or so.