New tank, sand or gravel?

It's mostly a matter of personal preference. I have both. One tank with sand and a few with gravel. The biggest reason why I like the sand tank is because cleaning is so much more easy. In a gravel tank you have to stick the syphon into the gravel to suck stuff up. A lot of the poop or anything else gets stuck in the gravel. With sand everything just kinda floats along the top of the sand. This makes it very easy to vac. Just take the syphon and run it along the top of the sand. All the poop etc. will get sucked up, and usually you get a minimal of sand getting sucked up. I've even accidently stirred stuff up and the sand still just falls back down(this happens once the tank is cycled and the sand gets weighed down by the bac.) The down side is you have to be careful not to stir up the sand too much or do it very often. Gas can get trapped and once it goes bad you don't want to release the toxins. Mine only has about one inch of sand and my convicts love to play in the sand so I really don't have to worry about it at all.