[NCguy]

Ok..Here's what I would do...Go ahead and get another 20 gallon going as a sump. After your tank has cycled add your fish and corals to the 72 but not all at one time.Add a couple then wait a few days...check your water..add a couple more...and so on. This will give your system time to adjust to the new bioload. Once everything has been added,your 20g holding tank can now become your fuge. Don't stir up the sand,just add some chaeto and a light and you're all set.