Using a false wall

[Kryten]

I'm thinking of putting a false wall in my new 66 gal to create a 3-4 inch area behind where I can hide all my stuff (only have 10 gal sump/fuge full of chaeto), including all my powerheads which are controlled by my wave machine. Obviously I'll still need some loc-line or something to put the flow back into the main tank, but it should clear up a lot of visibility. I was thinking the entire wall could be an overflow. Not sure if I need to completely seal the sides and bottom or if some gaps would be ok/beneficial.

Any comments and suggestions would be appreciated.

Thanks,