Rovers right about the die off, one other thing I would caution you on is the die off from the portion now buried in the sand. I elected to go dry rock for my base and put some cycled live from the lfs in to help seed.
I'll also throw in a plug for Bio Spira. Its bacteria in a bottle and it let me skip the weeks of cycling ammonia and nitrites.
Not sure what your target is for the tank, if its more towards predator FOWLR I can share some experiences. Good luck, feel free to PM anytime.