I have a heavy stocked 190g and 10 mins after a messy feeding, my water goes crispy clear. 2x ac110s do mech, fx5 mech/bio, and a 55g wet/dry mostly bio. I find sumps are terrible mech filters, even with socks overflows just don't seem to be able to pull alot of particles from the entire tank. I know your tank is much bigger, I would run a few fx5s to do some good mech filtration for ya.