Nice idea you came up with. I will love to see some pictures once you finished your project too.
what if you did two pipes coming out of the box similar to a fish bridge. The current in your tank may be enough move water through. I did a fish bridge between two ten gallons and found my fish used it (even though it was just pvc). Here is a crappy pic I took with my phone...
Clear PVC is super expensive. If you decide this is something you want to do you may want to consider clear acrylic tube, its much cheaper (can't remember prices but do recall seeing some stuff that would have been affordable had I decided to make this permanent).
The TV looks sooo boring in between those two tanks.
Who would wanna watch regis and kelly when they can watch swimming african cichs
those 2 55's are begging for a bridge!