The overflows are two 50m bulkheads in the back of the tank, vertically staggered to work like a Herbie type system (with one pipe carrying most of the water at full siphon and the other just taking the small amount left over). The sump has a settling chamber then four sheets of Poret foam (10ppi, 2x 20ppi, 30ppi) which is mainly for mechanical filtration, then 50L of Pond Matrix and some bioballs for biological. The settling chamber provides a good place for the Pothos to grow, but TBH I wouldn't bother again as the Panaques seemed to stop making a lot of sawdust once they got to about 20-25cm. The Poret has been great for mechanical, the water will never be gin-clear but the fact I can go away for a month without having to worry about it clogging up is a huge plus. Only problem is it wouldn't work if the sump was under the stand as the sheets are 50x50cm so the sump needs to be at least 55cm deep then you need space above to pull them out for cleaning. The Laguna pump has worked flawlessly the whole time.
Next time I'd possibly just use the Poret foam for mechanical and bio, maybe eight sheets total. If I had the option [here in NZ] I'd seriously consider something like a WLim bead filter or Ultima instead of the current set up, all depending on space etc.
I'll get the photos next time I bring the harddrive home.