The resin from the smoke has probably leeched very deep into that Oak stand. A good sealant might be able to cover it up, if you want to take the time to re-do the stand.
Your best bet would to just build a new stand. The glass tank should come clean with some cleansers.. I can almost guarantee you it's the wood.
Your best bet would to just build a new stand. The glass tank should come clean with some cleansers.. I can almost guarantee you it's the wood.