both for shure, its the only way to get the bio filtration you need... btw get a book, it will help you with a lot of your misc questions you have. some people like to go without sand, but again you would have to lower your bio-load (amount of fish and waste producing animals in your environment) because the live rock alone cant keep up with the nitrate cycle. basicly your fish produce waste. that waste has ammonia in it. ammonia is extreemly toxic. that ammonia is converted to less harmfull nitrites, and then even less harmfull nitrates through a process called the nitrate cycle. if you dont have live rock or live sand, there is not as much bacteria to make this process work. so yeah plain and simple you would want live rock and live sand
