Go to a fish store, and I mean a real fish store, not *****. If money is no object, just tell them you need filtration for a 200 gallon tank, but compact enough to fit in the stand of your 100 gallon. Since the 100 gallon is still a bit small for a mature adult Porc or Dogface you're going to have to accomodate it with serious overkill on the filtration. Get a skimmer for a 200 gallon or larger and a very large sump.