Rinse the sand in a bucket first, swirl it around using your hands, then poor out the dirt etc...When adding to the tank turn the filter(s) off and wait for it to settle.The water will probably be a little cloudy, but once the filter(s) is back on it should clear.Then, rinse the media, and job done.
i was only going to add about another inch or so. i don't think i need to remove the fish for this?