Dollarz,
I would rethink that. The two different substrates will mix, no matter how hard you try to prevent it. Crushed Coral just cannot provide the oxygen free zone necessary to eliminate nitrates.
Read about it here:
http://www.rshimek.com/reef/sediment.htm
I see that you are on the east coast, you should be able to get Southdown. IMO, Go DSB exclusively, and forget the CC.