After a lot of research and checking out reviews from Australia, England, and Canada, I took a chance on a Fluval for the first time (I've always used Eheim and wet/drys before) and just got an FX5 to replace a big wet/dry with a Magnum HOT for my 180g tank. I rarely was able to get the crystal clear look to water and after several years, just wanted to try something else for a while. I got it set up a couple weeks ago and my feedback is this: There is a lot of talking about the micro chip and faulty design etc---I have watched my unit click off for the 2 minute interval a couple times--I think this is a back up--so far, no air is dispelled--if you have it set up right, there is no air exposure--it is great for initial priming and a back up otherwise I think. No big deal. Second--the water is CRYSTAL CLEAR--this is a heavily planted tank with 10 discus and a bunch of bristlenose, etc--the usual. I changed it up a bit when I set it up: Put a big sponge on the intake, changed the output to a T barred spray bar at the bottom of the tank that is about 3 feet long in total. I also cooked up a CO2 reactor thing that is working efficiently by drilling out one of the end caps, siliconing in rigid airline tubing which extends out about 3 inches; CO2 black tubing is on the outside line and there's a micro bubbler on the internal side; screwed it back together--water flow against the bubbler is breaking the CO2 bubbles up with great absorption and they come out the spray bar holes--a regulator, etc keeps the pH where I want it and everything is neat and out of the way. I like the spigot on the bottom for draining off water also--most of the debris is at the bottom and it keeps the filter cleaner and efficient.
Anyhow, so far I am really happy with the FX5--also, it is QUIET as hell--virtually silent. Time will tell, but so far I'm pleased! Just some feedback.
Best regards,
Harriett