hey b/l ,
i wouldn't top em first time around , if they blow up like mine do from it i don't think your lights will cover all 12 .

as far as your p/h flux. try adding 2 more holes n grommets in your 13th. bucket . 3 lines total , 1 for each row of plants . it'll be more apt. to draw nutes evenly from all rows of buckets then -n- recirculate more efficently.
peace
merry x-mas
the crispis