Hi livloyalist,
1+ on what Peter said. Using some of the old water may help too...
But you must make sure you have not allowed any die off in the live rock and filter media during the transfer. i.e no drying out, no stale water for hours, no extended freshwater soak etc..
When I migrated from my old to new tank, i actually got new live rocks and new media and went through a couple of weeks of cycling and introduced my fish without problems.
I wanted to reuse some of my old media so i transfered them to the new sump as well.
However, I made the mistake of keeping my old filter media in a pail of water without flow or pumped air for hours. Hours after I introduced the filter media, I found all my fish in hiding and near death. In the end, i was very fortunate to have only one death after I rescued all survivors and put them back into the old/quarantine tank. I believe the old media experienced die off and release some toxins into my tank....