making close loop system

[banditpowdercoat]

Ya, The overflow drains to the sump, where I will have a mag 1200 pumping into the loop, via the PVC in the back. Sorry if thats not a closed loop???? I was under the impression that the Loop itself, is what they call closed loop, because you allways have a drain and return from the sump???

And on hose clamps, Plastic is the only thing for inside the tank???