Also be aware of some issues with draining right to the basement. I have the same setup with my 150G, am running a single overflow with 1.5" drain and 750 G/hr return. Even with the durso it is quite noisy due to the shear drop (even though there are two 90 degree angles in the drain pipe). I have to keep the top cap off the durso otherwise the water creates a siphon and drains to the bottom of the durso opening , like a toilet flushing (and sounds the same)!
Case in point, I would go with a single 2" drain and overflow and minimize the amount of flow going to the sump. It just isn't needed. Instead I use a Tunze 6100 powerhead to add water movement in the tank, with plans to add a TS/25 kit for a total of almost 10000 G/hr flow!
