35 gallon hex.

I want a gentle flow in the sump 1st it is small, 2nd I want live sand and plants growing out the top. (mangroves & some different marco algae)

I do not have an overflow currently, I am still deciding weather to drill the tank or not. It will have one return, it's a hex so if drilled I want minimal holes. One return no matter what.

Size of plumbing I am not sure of, you may offer suggestions for that too

I know I need to lift the water 3 and a half feet back up to the display.

Think like a gentle refugium with a hob protein skimmer