There is one way of placing sand in the tank without a major dust storm. I wouldn't do this though unless u absolutely think it is the sand or u no longer like the sand u have chosen. After the removal of the old sand u can use a pvc pipe and place it at the bottom of the tank. U can then begin pouring sand into the end of the pipe sticking out of the water. Fill until u reach the desired depth. This won't stop all dust but as u can possibly imagine it will cut it dramatically. I think it was Tracy that suggested it on another post a while back actually. Anyway, the source sounds like something other than substrate though. If it is a new tank ur substrate shouldn't be putting off an odor unless it is "live" and experiencing a die off. I would check other sources as the problem. Also, I wouldn't mix the two u may end up trapping bacteria that u don't want and the main reason why people don't like to use crushed coral in the first place. Since u are replacing do it all if u can.