Im curious. Obviously the 120 isnt going to be big enough long term. But filtration-wise, would a 30 gallon sump be considered enough filtration for a well stocked 120? Reason I ask is I have a 180 with a 50 gallon sump as the only filtration. Tank will be somewhat heavily stocked, though not sardines in a can packed!I have a good turnover through the sump- 10x and it is has a bunch of bio filtration. What is the general consensus regarding a sump as the sole means of filtration? Way I see it I could get and external, but whats the point? I have way more mechanical and bio than i could fit in several fx5's if i was going the external route with no sump. What does everyone think? Thanks