Heh, more than likely it's my cube, I still haven't got a chance to pick it up yet
Livestock plans sound good
I'd go with a Seio for flow. You can take off all the housing and make them Tunze style, they work great like that. I'd definitely use that...
As for clams, you could easily do it. I had a Crocea in a 20g with no problems. But, wait a few months before adding one.. let everything stabalize and mature. (yeah, it sucks.. but its better than wasting the cash)