Go with whichever you like best. I started with cc over about an inch of sand and got tired of all the gunk it caught and trying to keep it clean. I did not have nitrate problems, I switch to dsb only because I liked the look so much better. Don't mix them though. Also, you won't need 120lbs of playsand in a 30. If you go the dsb you'll nedd at least 20 lbs live sand on top to seed it and live rock. Here's a link that might help<a href="http://rshimek.com/reef/sediment.htm" target="_blank">dsb shimek</a>