Another disadvantage if a remote sump is that if the drain is long and winding, with any horizontal sections the drain gph is greatly decreased. Its a gravity drain after all, and the most efficient gravity drain is the shortest, straight down (recall your trigonometry).
My family room 180 has a 60g sump under it, and any leaks from the drain go into the sump water. I have 3 returns.
1st return goes from the sump 2nd compartment straight back up via internal pump to the center return. This pump is on a battery backup, even though the whole house has a 14kw natgas autoswitch generator- its that important.
2nd return goes from sump last compartment out the wall into the garage to all the closed system add-ons like chiller, & UV. It re-enters the house near the sump and climbs to the 2 side returns barely under the water line. If this pump or pump 1 fails, & the check valves fail, back siphoning can only add 5 gallons to the sump, whoch it can handle.
The 3rd & last return comes from sump 1st compartment, out into the garage to the open system add-ons like the skimmer, top of the elevated fuge, skimmer, ozone, etc. it feeds into the fuge last from the top, the fuge drains into the DT from the top, both to prevent back siphon.
Water changes can then be done from the sump, or the skimmer/fuge line the garage, via plumbed in 65g mixing vats / ATO vats.
HTH
