Aquired a 12g nano cube with live rock, two chromis, a few Palys, shrimps, snails, and hermit crabs. It has a small amount of sand in it, nothing to talk about. I want to add about a 2" bed of dry sand, Tropic Reeflake, I have left over from a new 75g tank setup. Do I remove everything, add sand on top of old sand, put old water back in with live rock? Will the system cycle again?