Did you add anything besides the sand and crushed coral to start the cycle?
I too started my first saltwater tank with crushed coral. And man did I regret it. In fact, we have a "Worst Advice You Were Ever Given" thread on here, and that's what I put down as the worst advice I was ever given. Not only will crushed coral trap poop and uneaten food, but digging animals that are essential parts of your cleaner crew (and digging fish) can't live in it, so there's nothing to clean it. It can lead to a nitrate factory, making it impossible to keep animals -- which is what happened in my first tank :(
It's easy to remove it all now while you can, and replace it with sand. There's no need to spend the money on live sand vs. dry sand. It's kind of a scam -- dry sand will become live sand soon enough on its own.
But then you need something to start the cycle. The tank just won't cycle on its own. Usually, live rock does the trick. You should have 1 to 2 lbs of live rock per gallon in your tank. To save money, you can buy part live and part dry rock. Live rock will serve as the main source of filtration in your tank, and it's probably the most important component of a saltwater tank -- more important than any expensive piece of equipment.
After you've got the rock in, you can jump start the cycle by throwing in a raw piece of people food shrimp, or some fish food, and just let it decay. This will cause the cycle to begin. Never use a live fish to cycle.
If you're just sitting with a tank filled with water, sand and crushed coral, then nothing is going to happen on its own -- you need to add something that is rotting to start the cycle.