Switching substrate
 

Ok, my family is moving pretty soon. Do you think that when we move, I can switch the crushed coral substrate with sand? I figure that I'll have to take the substrate out anyway to make it light enough to move.

Yes you can. What I would do is save a big mess bagful of your crushed coral so when you set up the new substrate you can set that on the bottom to somewhat seed the sand with the bacteria form your old setup.