Moving 29 gal Biocube

[gobytron]

I would leave the sand in, as long as it stays wet, you should keep some of the beneficial fauna in there.

You can do as you described and just put the rock and water back into the tank, especially since you don't have any fish. If it were me, Id use 50% old and 50% new water.

you shouldnt need to feed the tank anything.
You don't have to leave the lights on at all if you have no coral or fish but leaving the lights on for the usual amount of time (8-12 hours) you might see some unexpected growth of an organism or two...