Look at Yeskamaster's results. The system you have in mind is like 12 of Yeskamaster's Waterfarm hydro units except without a main resevoir controller thing. His cost like $40 each. You could get six of them and get a 1000W HPS or MH, and get great results for about $500. I think that a twelve bucket system would need more than just one 1000W light for optimum conditions and effeciency, especially if your growing large plants with maximum yield potential. It's a terrible feeling when you grow your plants, but you wished you had more or better equipment. 6 buckets of plants could take up as much as 36 square feet of grow space and need for light. Thats 6' by 6' and I think a 1000W system would just cover that. It will save in your usage of nutrients, and water consumption. If you have a big room, like 12' x 12', I would use at least 2 or more 1000W ballasts. I've seen 6000W of light in 12' x 12' room but there were over 65 plants in there in a dirt grow.