For 12 plants you need each set of 3 to have it's own rez. They have to have different nute schedual and flush at the end. If you have the space and can cooltube and vent and A/C the room I would go 1000 HPS hortilux or sunmaster bulb with digi ballast.

They came and took my sea of green. 12 plants 6 to a 10 gallon tub, Harvest each month was 3/4 to a pound depends on the strain.

Look up locnar1958 and see my grow.