That stuff is as old as I am, maybe older lol... I'd just rinse the heck out of it. How was it stored?
125g semi planted. 2 silver angels, 14 silver tips, 16 white fin ornatus tetras, pair of Nicaraguense, pair of nototus severums, trio of firemouth cichlids. 2 FX5s, 1 1500gph circ pump, 2 48" LED lighs, and a HUGE piece of driftwood.
650g fish room. 15 30g tanks, 150g sump.