Brightwell seems to have copied stuff off the others, the guy is a marine guy, not a plant guy. It'll cost you an arm and leg to run it and you'd be much better off using basic dry ferts. Unless you want to pay for water......with a tiny bit of fertilizer added to it, and more for shipping the water.
Overflow: Make this a Bean animal style over flow, do this right.
Sump: Sealed inflow, then gentle spill over to the filter socks(I'd run 4 4"-7" dia socks), maybe a 36"x 18" x 18" sized sump.
CO2, likely a Rio or similar 300-600gph feeding into a 20" tall Clear water filter reactor housing. Rio in the mid section of the sump, out flow near the return pump.
A Little Giant 4(1225 gph) ought to do the trick for the return, fairly quiet.
Sediment, your choice. I'd still get the ADA AS. Maybe UP AQUA's soil.
I'd seriously consider a Vortech MP40, maybe a MP60, you'll need the extra flow. You can get decent deals on Reef Central's used goods trading post.
T5's are good, but you'll need two fixtures, say 2 x 4 or 2 x 6 bulbs, one at each end since the tanks are 36" front to back, no single light will make that distance spread. You can DIY or buy a pre made light, I like ATI's with the dimmers.
Spend the $ here and not of ferts
Do one Dutch and then the other nature style you'll work yourself to death otherwise.
Start sourcing wood and rock now.
I sell pallets of wood to one of the vendors who happens to be in your state.
If you need sometime larger, cool, I can add to a pallet order.
Clean the tank with a razor blades and vinegar etc. Use fresh blades often to prevent scrapes. Tooth brush and bleach to get any algae or other stains off.
Open top for both tanks, you'll be in/out of them often, so have good access.
Dual stage nice CO2 regulator set up.
KH test kit(Hanna is a good one)
20lb tanks, I'd keep say 4-6 tanks around.
A box or two of dry ferts, DTPA Fe also.