My girlfriend gave me a BioCube 14g for my birthday about six months ago, and I have subsequently ended up becoming a total reef nerd

. I added my live rock at the beginning but now that my tank is settled in and I'm adding more coral I realize that the pieces I bought may be too big and bulky (forgot about coral growth and water flow...). How do I go about changing the rock / aquascape properly without risking a large cycle?