I know alot of people don't like them, but I've got two Marineland Magnum 350's on two 55 gallon tanks and I love them. They're quiet, keep each tank crystal clear, and cost alot less than other 350 gph
filters. They're about $95 bucks from BigAls, and I've had no problems out of either. My only real gripe is when you have to prime it after cleaning. The water flows into the top of the cannister, through the media, and then through a pipe feeding from the bottom. That tends to trap air in the canister when you refil it, so it won't self prime. You can either prefill it before you put the lid back on, or open the outlet valve first, then the intake. That'll let the air escape through the intake strainer, and draw water in from the spraybar. It's a little annoying having to open them in the proper order, but it's not a huge deal.