[Chin_Lee]

I had this configuration with 1" return and two 1.5" drains. For pump I used Reeflo Barracuda and it provided enough flow for my np pellet reactor and main tank circulation. I put one of those accelerators on the output and it was the only water movement needed for my 165g lps/softie tank.
Pros-it kept the tank cool during the summers and the ambient noise of skimmer and other devices are minimized. I was also able to use the cabinet space under the tank for the kids to put their toyes or why. All ur equipment is out of sight, out of mind in the basement
U can go BIG with ur sump size!!! I had a 180 sump and a 165 display upstairs. Lots of room to put extra live rock, equipment, hospital tanks, isolate fish etc

Cons- electrical consumption of the pump was about 300-350watts and that runs 24/7/365 which dramatically increases hydro bills. Also the pumps humming noise radiates through the hoses in flooring and there's nothing u can do to minimize the humming noise from a big return pump.

Recommendatio: if u decide to herbie, put the gate valve closer to the overflow box upstairs probably under the tank. Its easier to control 3-4 feet of head vs 10-12 feet of head in the basement. Its also easier to control being able to visually see/hear the water level in the overflow than trying to run up and down the stairs to the gate valve in the basement.