Ok, so I have reviewed what we are working with here...
I would reccomend the following...
Take 16 clones from the bigger plants that are identified as female Now, and stick them under another the t5's in another room now. Root them and veg them under the two t5's lights you have.
Then huddle the plants into a 3.5x3.5 square and lower the 400HPS to within 18 inches of the plant canopy.
Switch the light to 12/12, and watch very carefully for signs of male plants over the next two weeks.
Also at the beginning of 12/12 stop feeding a veg forumula and begin feeding a Bloom formula of nutrients such as Supernatural Terra Bloom powder, or Fox Farms products
See hear for info on Fox Farm products...
FoxFarm Soil & Fertilizer Company
click soil, and get every product ie (Grow Big, Tiger Bloom, Big Bloom and the three solubles (Open sesamea, beastie bloomz, cha ching)
These nutes are cheap and they do great for soil plants being grown in Fox Farm Soil.
As these plants show there sex, keep the fems and kill the males off.
Hopefully we get a 50/50 ration of better and end up with at least 15 females.
Now since some of your plants are taller than the other, you will need to level the feild, you can use cinder blocks, or anything, just get creative with it and get the tops all level with each other.
Also because some of your plants are taller they will yeild a slight bit more, but they should be spaced out into our 16 plant canopy to help light get down into them.
Think in rows....
Remeber to make sure there are NO light leaks from under the door, step in the closet with the light off and a bright light on outside the door to be sure...
8-9 weeks after going 12/12 we can hope to harvest plants with a average weight of 20-28 grams a piece. thus making you just under a pound of high quality cannabis...
Repeat with the clones you took now, that were vegging for a while, and select the phenotype you like the most and keep it as the mother for your "system" and at week 6 of flowering the above plants cut 16 clones off of her to use for second go around)
Good luck...
GG