Just wondering if this is doable or not. The drawing below is a rough draft to say the least, and it's not to scale. I'm assuming that in order for it to work the lines going into and out of the sump need to be much narrower than the main intake line of the FX5 so that the sump isn't overwhelmed by the pump's strength.
My vote is this will not work... your FX5 will pump water out of the sump faster than it can siphon into the sump. OR your FX5 wont keep up with the siphon.
Either way I smell disaster..
Most ppl run an FX5 for mechanical filtration along with a sump for bio-filtration. I would suggest getting a little pump that will let the sump work on its own.
The whole idea of having a sump and a canister is to differentiate the two as separate units. If one unit fails the other has the back up capacity to handle the tank. By only having one pump in your system your defeating that purpose, so if the pump fails on the fx5, all your bio media has the potential to be ruined.
So the line to the sump should be setup as an overflow, the line to the FX5 is full siphon, this line may siphon into the sump. This will happen for sure when it not running.
Also a sump works by over flow and blanceing water pumped into the tank where as the canister does not and combining the two does not seem like a good idea.
If the running hieght of the sump in near the same hight as the tank (as all caanisters need) then you could have tank water flow into the tank and have the FX5 pull from the sump and pump back to the tank.
You would want to make sure the overflow into the sump could flow much faster then the FX5.
Do you already have the FX5? seams like you could build a full sump for less then the cost of the FX5 and media to fill it. esspecially if you want a small sump anyway.
