Watch out for c02 in a people living area. It is heavier than air and can flood out oxygen and kill. Just a heads up. Be carefull around people.

A 400 hps will do pretty good but mine would grow right into the light and burn the top off. I got a good yield just burned tops. That was a small drip system not DWC, 3 foot is as high as I could get for the light to do well.