I like to use 2 gallon pots. They take up about a 1 square foot, i pack 30 under each 600 watt HPS. Ideally you want to get 2 lbs per 600 watt light with optimal conditions. My clones root in one week and then I veg for one week, then go to 12/12. The clones are around 6 to 8 inches tall when I start 12/12. The ending height will be around 3 ft tall with each plant yeilding and ounce or more. Also I suggest using a super spreader for the lights. I just found out about this contraption that fits right underneath the HPS bulb. It really helps eliminate hot spots and also allows you to place the light closer to the plants. The only place that has it is the company in Australia. Alot of Euro growers use them.