what size of space for 600w hps with cool-tube ?

hi RUI members.
i bought a 600w hps with dimming options and 6" extractor fan and 4" intake fan rated at 550m3 and 220m3. I am also designing a new grow cab.
here come the question.
would I have better coverage from the light if the cab was 1m by 1m or will 1.2m by 1.2 be good for the light to cover the whole area ?
i'm going to use the scrog method so i want all of my tops to get the "same amount of light".

peace

I think you would be better off with the 1.2x1.2 space. A 600 watt is easily enough light for that, and unless you're injecting CO2 you will be wasting light with a 1x1 space. Here's a guide to lighting that explains everything you need to know.

agreed. 1.2x1.2 meters will be fine with a 600.
the dimmable ballasts are great, what brand did you get?