Marineland Tidepool systems are very good and less expensive than canister filters. The huge bio wheel can house millions on BB and can be connected to another very easily via bulkheads and some plumbing. The new Tidepool systems have a double bio wheel per sump. I run 2 Tidepool systems connected together with a 600gph pump for my 240gal FW aquarium and my water is crystal clear. The tidepools have 4 trays allowing you to combine many different types of filter media from polishing pads to bio balls and are very easy to change. With 2 connected together i get double the filtration and only have to top off one. I would reccomend this system for its huge filtration capacity, easily connectable to other systems and fairly inexpensive when compared to canister filters. Why would you NOT want a Tidepool system?