bcfd144 meant to say clown loaches or clown knives, not clown fish (which are a saltwater fish)
thought i'd clarify that so that there was no mixup on the OP's end.
i have a 300gal tank and i personally recommend a sump over canister filters for a tank that large. i would never dare run a single fx5 on it, the flowrate is simply too low, and their capacity for biomedia is terribly small compared to even a 30 gal sump. you'd want multiple canisters on that tank, which is going to cost big $$$ and not be as effective.
i run a 90gal sump with a 3 drawer trickle tower. each drawer is 2.5 ft x 16 inches x 10 inches tall and is filled with pot scrubbies.
my pump runs 1800 gph at no head.
i have a fluval 405 on the tank that i keep on for alternate tank quick setups, as well as a sponge filter in my sump that i can pull for any hospital tank setup needs.
i can literally go without water changes for over a month, if not longer (i don't wish to test this though lol), but for the sake of the fish, i like to give them fresh water weekly.
sorry about your mixup with the florida ray, but you wouldn't have legally found a seller in florida for freshwater rays as they're illegal in that state. only research facilities and such can keep the freshwater ones with a permit. please read the stickies in this subforum if you haven't. there is a ton of info in them alone to get you started.