400w enough for my grow?

I have 15 seeds and would like to grow them all at the same time. I got the auto pack from m-s.nl. It has 5 auto white widow, 5 low ryder 2, and 5 auto berry. My grow room will be a closet that has a footprint of a little under 7' x 3' of usable space. Basically up to 20 sq ft of floorspace. I was looking at a 400w HPS/ MH switchable lamp (http://www.amazon.com/Digital-Switchable-Ballast-Reflector-GYO-2002/dp/B003810CVA/ref=sr_1_2?ie=UTF8&qid=1294351663&sr=8-2). So 15 plants would take up about 15 sqft right? At 2,000 lumens at 15 sq ft that would be 30,0000. But would one 18.5" x 15" lamp be big enough for this with reflectors all on the sides? I would probably create a roof at about 7'.

Also, has anyone tried using that reflective "insulation" they sell at lowes and home depot? It comes in rolls of different lengths.

U should try getting a Light rail I got one for 70 bucks on sale and put it in my closet, The plants hella evened out after I put it in.

for 15 plants i'd go with 2 400ws, you can fit about 4-6 one ounce plants under a 400w. How big of plants are you going for and what sized containers do you plan on keeping them in?

idk man ive honestly never run auto's but 15 sounds like too many to me...i usually run a plant or two under my 400 watt light...especially if it is your first grow i would go a couple at a time as a learning experience

I grow 6-8 under my 400 that have been vegged to 18-24". That is about the max I can do with the 400.

Wow, you guys answer quick. I was kind of thinking it might not be enough. All the plants are in the very short category, probably 1' - 1 1/2 tall. Do you think 1 gallon pots would work or would they be a little small? If Tommy can pull 6-8 2' tall plants under a 400w I shouldn't have too many problems I guess.

Tommy what size pots do you use? Do you start them in it or transplant? Just wondering if you even transplant auto dwarfs.

I have never grown the auto flowers. I use 3 LB coffee cans or 3 gal buckets for flowering and I grow hempy style. I can fit 8 plastic coffee cans or 6 (3 gal) buckets. I start them out in 20 oz coffee cup for the first few weeks and then into the final container for about 5 weeks. It all depends on the size of the clones as to which final container I go with. I use all the same type in any single flowering cycle.

for a few $$ more you can go to a 600watt for $250 from HTG Supply.