I'm lazy.
I'd run carbon, maybe some Chemi Pure.
If you don't know for sure what got in there, it's tough to do much more than try a blanket solution.
If that doesn't work, how hard is it really to redo a nano?
You probably have a stash of new sand and LR (don't we all).
Then again, this comes from a guy who never feeds or does water changes.
