I don't want to rain on your parade but I have never yet seen a seed-to-harvest aero grow. Flowering at 1.5 feet means finishing at 3 feet, and each plant will have a huge root mass by then- look at Weedhound's old logs to see what happens when your root ball becomes too large for a hydroponic feed/water delivery system to penetrate. It ain't pretty. Also, a 400w light isn't going to give you the penetration you need for 3 foot plants- you will HAVE to screen them, but they will be so large that they will crowd each other. The aero systems I'm familiar with have spacing of 8-12 inches between sites. Bent over, a 1.5 foot plant will cover the next 2 sites.

Start your seeds in another system, or in soil (that would be my choice). Sex them and flower clones when the clones are just double the size they were when cut from the donor.

IMVHO aeroponics is the worst-suited type of system to grow large plants.

HAve you got a few grows behind you already?