I have lways felt that the amount of yield is directly related to the watts per square foot. With a system like that I would go with 3 1000 watters. Two mh/hps switchables and one straight mh in the center of the other two. Use all three as MH for veg and switch the two outside ones to HPS for flower. I have always liked a full spectrum for flowering. Sunlight supply makes some pretty good ballasts and hoods. They make one hood I am fond of. It is a horizontal burn. Super Sun Reflector is its name. Real easy to make into a vented hood with optional parts. I always steer people towards www.stealitback.com under the home and garden section and in the commercial nursery supplies sub section. They always have hot deals. Anyways, 3000 watts at least if you want it to be worth your time. You are doing this right by researching and asking questions. Already props in my book. :thumbsup: Take your time to review everyones input and make an educated decision. For most peeps this is a major investment. To calculate your minimum air requirements take your width times the lenght of your room and divide it by two, that is the minimum in cubic feet per minute (cfm) you will need to properly vent a room. Have you investigated into Co2 enrichment? My newest venture will have a 265 cfm blower venting about 4 square feet by 4 feet tall giving me 16 cubic feet of air in my cab. That means the air will be refreshed completely 16 times per minute. Thats like once every 4 seconds. Wow, thats the first time I ever actually calculated that out. Anyways if you got more questions, feel free to ask