Check this link out lots of good info! This is coming from a CC kind of guy LOL!
The following is qouted from:
How To Setup Your First Marine Tank
The best substrate you can use is a fine aragonite sand. At the local fish stores (LFS) you can find brand names such as ESV, Aragamax, and CaribSea. These are all pretty decent choices, but can be expensive. For a less expensive route, check out your nearest Home Depot. Look for Southdown Play Sand. It is a very good aragonite sand and has fine particle size. It will cost about $4 for 50lbs. as opposed to the stuff sold in the pet stores for $30 for 30lb bags! Below is a picture of two different types of sand that are calcium based for aquariums.