I say put it in a container with saltwater and a powerhead. Let it run for two to 3 weeks and check for nitrites. If after 3 weeks you don't have any THEN place them in your display tank.
I would want to make sure its cycled and not releasing anything into the intended display. So.......bdare's suggestion seems best to me, being that you have a 2 yr system. You don't want to mess that up !! Just a precautionary measure.