tank+sump+refugium question

[the_buzz_m]

I have a 75g Reef Tank with built in overflow that goes to a 30g sump located under the main tank. From there, water is pumped back into the main DP. Obviously, this is the normal way things work. I have now been given a 55g long aquarium and am thinking about adding this one into the system. I want to use this one as a coral/refugium tank that can supply pods to the main tank as well.
What I am thinking of doing is making the return pump in the sump go to the new tank and then place an overflow box (lifereef model) that will flow back into the main tank. I figure that with this method, I still only have one pump and shouldn't have to worry about one pump failing and the other one causing a flood. It would also increase the overall water amount.
Another benefit would be that my wife and I wouldn't have to fight over which manderin to get. We could place one in each tank.
Does anyone foresee any problems with this setup or have any other suggestions. I am not that familiar with the overflow boxes, but from what I read.....this should work.
As always, I appreciate your help!
the_buzz_man

 

[dogstar]

Worth a try, the 55 with the new overflow would have to be higher than the 75 and dumping/draining into the 75 could put bubbles in the water and current would not be forced/jetting around in the 75 but overall GPH would be the same..

 

[the_buzz_m]

Would it be better for me to put a second pump in the sump that brings water to the refugium and have the overflow go back into the sump. In other words, I would have two tanks running through the same sump.