Any new sand was well washed dry sand (if there's a bigger boondoggle in this hobby than 'live' sand, I've yet to encounter it). The reused sand was not rinsed, though in the process of removing it much of the detritus drained out. Probably most would recommend not reusing old sand, but mine contains so much life I wanted to maintain the biodiversity.
As noted, I am having a bit of an issue with STN, though I would attribute that more to alk shifts from needing so much new water. Probably should have adjusted the new water in retrospect.