A customer of mine from where I work came up with this, and asked me to find holes in the idea.
I've yet to find any, but I want other opinions and I'm open to suggestions.
Here's what's going on, and a quick sketch of the idea plus my explanation.
Water from the overflow spreads over a tray of 6 filter socks, and proceeds into the same tank where it is passed through a skimmer. The water then flows through the side of the tank by gravity to the 2nd.
(Each tank is lower than the previous)
In the 2nd tank, a simple refugium with all it's necessities. Then, down to the third where one pump returns to the display, and a second pump in the same tank pushes water back to the first tank to go through the process again.
Each tank is a 40 gallon breeder, housed under in the stand of this 300 gallon tank.