[midgetwaiter]

The combo of the clown loaches and the butterfly loach is interesting. The butterfly loaches prefer cooler (higher oxygen content) water and the clowns usually much warmer. What temp do you keep your tank at?

A sump sure makes life easier with FW too, worth looking at if you don't mind spending a bit more money on the setup. A river tank is a neat idea but if you crank up the flow rate mid water swimmers will be tricky, most of the little schooling tetras are from pretty slow moving streams and pools. I'm actually having a pretty tough time thinking of something to suggest.

Your loaches are still babies, just wait until they get over a foot. Your ideas are all solid though, should work out fine.