dcca

A 20w CFL (from UK hardware store) produces 2000 lmns of light...so thats 100lmns per watt.A 400w HPS (from net) produces 45k lmns of light....so thats 112.5 lmns per watt.
Dude ...thats 45k=45,000 lumes compaired to 2000 lumes right? How do you figure it is not like 22 and 1/2 times brighter?
45,000 lumes divide that by 2000 lumes and you get what?? 22.5. Get it?
Your plants are looking for the light output. They can care less of the watts.(sort of). But, they do need lots of lumes. What you need to do is figure out the lumes PSF..Then you will know how many watts you really need to have a good grow.. So what i'm saying is that you would need 22 and 1/2 of the 20 watt flours to even come close to 1 400 watt HID. If I were you I would read up some more about lighting..Happy Growing!