I have a 150 gallon established tank. o o less than 20ppm, I have a sump and am wondering which canistar filter would be good. most depend on gravity to keep it flowing, right , and next to my sump there would be no drop to the filter . It would have to draw it like a HOB does. would they do that, I was hoping for the FX5 Fluval. thanks any sugestions would be great. I like the artical about multifiltration.