Thanks guys. When u say sand do u mean like regular play sand?? And live sand and dead sand?? does live sand just mean theres life in the sand?
No prob man... no, we don't mean regular sand. People really recommend against this because of some element in it that I think helps produce algae. (I'm not really sure... I think its like silicates or something like that. someone else will know better) Do not use crushed coral either as a substrate. Most people choose a sand that is designed specificly for marine use. My personal experience, I choose Arganite Fiji Pink sand. The great thing about getting sand for marine use is that it has natural buffers in the sand. This will help buffer your alkalinity and help to stabilize your pH.
When you buy marine sand it is not "live sand". It's just plain sand... over time you will have live sand. Tiny organisms/worms/etc will take up their homes in your sand. This is a natural process and is good for a tank because bacterias in the sand consume toxins. However, some people buy already mature "live sand" and mix it in with their "new" sand. This will encourage healthy growth in the sand obviously much quickier.
With that being said.. . live sand is not a neccessity. like I said, over time it will come alive. Also, live sand tends to be pretty expensive unless you can find someone to give you some or a crazy good deal. When I setup my tank, I didn't use live sand at all. A month later I have worms in my sand and all sorts of micro citters running around. Doesn't take too long.
Live sand is a great option if you can get it and afford it. Live Rock is much much more valuable. I'd rather spend more money on live rock, personal preference.
Hope that helped!