Hps lighting? What to get

HELLO FELLOW GREEN THUMBS

THIS IS GOIN TO BE MY 2ND REAL GROW I USED CFL ON MY FIRST GROW . I WANT TO UPGRADE TO BETTER LIGHTS BUT DONT NO HOW MANY HPS WATTS I SHOULD GET .AND I MADE A FLOWERING BOX THATS 2X3X4. ILL TAKE ANY ADVICE

that's a pretty tight area dude. I'd go with either a 250 or a 400 tops,..with a lot or air circulation.

maybe even a cooltube. that a tight area.

So 250w might be ok? Whats a cool tube and where could i get one

Or what about 150w