Just looking into the fx5 as that number seemed a bit high, and the gph is rated at:
as 607 g/h *
* Note Flow rates were measured with intake and output hoses of the same length and without media.
So not sure what it would be packed with media and what amount of head distance they were measuring at.
There are many sump pumps that do a lot more than 1300 gph, but again head distance must be taken into consideration. I have a mag 18 and I think I am getting maybe around 1300gph out of it. But I got it for $75, and the sump was all in for maybe $200?
I guess it depends on what you want, and if you already have the fx's already too. If you are set on canisters then that would be the route for you to go but there isn't a reason I could see other than space restrictions or personal preference not to go with a sump?
Either way looking forward to the final product.