as long as it goes through some good media flow rate is an open ended topic. you can never have to much filtration. i have a min standard of about 10x turn orver per hour in all my tanks, unless it is run off of an air powered sponge filter then the rules of engagement change. ex. i have 2 canisters on my 180gal. one fx5 with just shy of 600gph and a odassy with a uv light at 700gph, those are combines with an emperor 400 and hydroponics. this gives me a combined flow rate of 1700gph. now my 120gal that i have a sump on has a sump return rate of 1000gph. the sump has the main pumps flow rate combined with 3 hob filters with a total of 900-1000gph. i use hydroponics on that tank aswell.
so like i said you can never have to much filtration. the more you have the better it will be. i will be adding another fx5 to my 180gal and the 120gal in the not to distant future.
