Did you clean the sand before you put it in? The standard practice seems to be rinsing it through a pillow case until the water runs clear. There is a variation using a paint strainer from HD, but I'm not that familiar with it.
Since you already seem to be past that point: do you have a heater or a filter running? Be careful with these. The sediment may clog your impellor -- be sure to keep it clean. I also had a problem with settling sediment creating a hotspot and causing my heater to shatter.
It will eventually settle/filter out, but if you want to speed the process along I'd try a massive water change. Basically, pretty much refilling the tank. Directing the new water into a bowl at the bottom of the tank will help keep the current from throwing the sediment back up. I've also read of someone using a folded up pad of newspaper that floated up as the tank filled.
I use the current from the fill hose to blow debris I missed during cleaning up into the water column for the filter to catch. If you have a lot of fine sediment in your substrate it can blow up fast unless you dampen the force of the flow.
HTH