I would go with the FX5 out of filters I have actually owned but I am ordering an Eheim Pro 3 this week and I have a feeling it is going to be a lot nicer than the FX5. The fluval is definately better than canisters I have owned in the past, XP2', 3s', Cascade canisters but I am honestly not all that impressed with it. I think it makes a good filter for tanks in the 180 gallon range but right now I have it running in conjunction with a big wet dry and there is no way the FX5 could handle the tank by itself. I think they claim for tanks up to 400 gallons