IMHO what you have should be fine as long as the Fluval is clean. I have a Fluval 304, and a Seio 620 on my 33G semicube. The flow is adequate for my Staghorn.
BTW the Seio was probably not mounted properly if it made noise. I use the hang on tank bracket with two suction cups. I have never heard a sound out of it. Sometimes you have to use the supplied anti vibration thingy.
