I used this light calcuatot on a website and it said the maximum amount of light you need for a 2' by 2' area is like 330 watts of HID light anything more is a waste of power and a 250 works fine in this area. The only reason I say this is because in an area as small as yours, you may have some heat problems, what is your ventilation? also if you do have a slightly bigger area you could get a higher yield from your 400.
amstron Reviewed by amstron on . Lighting Stages Hey everyone I have a few questions on lighting for you guys, this is what we have to work with. Space: 2' wide, 2' deep, 4' high (can expand later on if needed) Lighting: CFL 20(75)watt Soft White, CFL 26(100)watt Soft White CFL 26(100)watt Warm White, CFL 26(100)watt warm white and then finally this 400 watt HPS system https://www.futuregarden.com/cgi-bin/shop/30-3115.html Now I know with the CFL lighting it is best to keep them 1" - 3" from the top of the plant but with the HPS Rating: 5