Overflow box,Closed loop question,Return Pump,HELP!

Overflow box,Closed loop question,Return Pump,HELP!



I'm planing a custom tank that will have a external overflow box with three 1" drains and one 1.5" drain.



I plan on setting up a bean animal with the three 1" drains that will be incorporated with a settling tank, skimmer and probably a Ehim 1260 for return over the top. This way I will be running about 600GPH threw the settling tank and skimmer(sro3000)



Question:

1) Can I have the 1.5" Drain from the overflow box to a return pump (iwaki 70) and have it feed two 1" returns drilled threw the bottom of the tank and also feed two 3/4" sea swirls over the top? Would that work for the closed loop?



2) Does a closed loop mean I can pull more than 900GPH threw the 1.5" drain?



Thanks in advance ;)