I put 60 pounds of live sand in my 29 gallon tank, and it helps keep my water nice along with my live rock. Mine was only cloudy for a few hours, my filter cleared it up fast. I think you should just use the whole bag and don't rinse it off because you will clean all the bacteria off.
Just add a cup over a course of the day so it won't be too cloudy. It will be cloudy thou!! Really cloudy, good luck. :-p
Fish Sticks, the best thing you can do with your dead fish.