you should have like 75 to 100w per plant,i read it somewhere in a forum...so i'm guessing in the ds60 u could fit about 4-5 with 3gallon pots and in the ds90 u could fit about 6-7..but wait till some pro gives you an opinion mate,again,i'm just a noob,i'm also waiting on some advice on my own grow ya know.i've just been reading about this too so i thought of giving some Help