Looks like a great tank. Sump looks great too!
Question, if you end up going with CO2, do you have any plans to seal to sump to prevent CO2 loss?
Im getting ready to set up a 240 as well (4'x4'x2') and was thinkng Altums as well, very interested in how your tank progresses! And thanks for the heads up on AngelfishUSA! They have some amazing looking angels.
90 Gal. Hi Tech. - Angels/Tetras/Pictus
65 Gal. Non planted - Ps. Elongatus "Chewere"