I have used every size of the aqua clear filters. They were alright but I found they clogged up too quickly for my needs and the impeller design really starting bothering me after a while with suction issues. I also have the fluvial canister filters 10-405, 306, and two FX5. I like the FX5s but I find the flow does not distribute enough. But I keep them running for 6-8 months at a time and love them for that ability. I hate my '05 series only because of the primer. It is just horrible and on some of mine they fail to create the suction I need and kill my fingers. Other than they they work very well. I love the change they did with the 06' series primers. Much easier on the hands.