So the tank on the left side is going to be planted? Will it be filled with some kind of expanded clay (hydrostone) or something that the plants will sink their roots into? Thats a lot of water even if most of it is grow media. You must be pretty confident the seams won't fail. If you have a good live planted area, then I'd doubt you need all the other water scrubbers and filters that you mention in the o.p. for the sump.

I'm sure I'm misunderstanding what is what and am anxiously awaiting the completion.

What creature are you putting in it?