I have a 75Gal with an Fluval FX5. It provides more then enough water movement, but I still have a power head with a sponge for two reasons. If the FX5 stops working for what ever reason there'll be some kind of back up. Secondly, I can take the sponge to set up a hospital, quarantine, jail tank by taking that bio-filtering capacity and placing it in the smaller tank.jgon_87 said: