I intend to convert a 3 ft tank into a sump.

[Backfromthedead]

I just like a big empty tank for my sump, then usually make some innovations in the plumbing or foam/media baffles instead of the usual compartmentalized sump layout.

I was really proud of my most recent innovation, $5 plastic chicken wire rolled up to contain the filter socks. This tank has a generous bed of substrate and moderately stocked so no extra bio media necessary atm.