Depends what you want to do.
There are many theories with substrate. Some run bare bottom, some run crushed coral (bad idea), others shallow sand, and finally DSB.
DSB - Deep sand bed, supposedly creates a denitrification process via bubbles of nitrogen gas after waste material is broken down. The gas bubbles then float to the surface harmlessly.
Hopefully others will elaborate, but I would research it on your own.
IMO a 1" sandbed would be for looks only and not do anything for the denitrification process
