cooltube setup questions

I'm getting ready to set up a new grow cabinet and I'd like to use a cooltube with my 250w HPS. The cab is 69"x25"x16". I'll be using a pyrex bake a round for the cooltube with either a stanley blower or dayton on the end.I want to leave one end of the cooltube open to suck out air from the cab. With the size of the bulb and the bake a round, there is only a total of 1" of air moving around the bulb. Since the source of the heat will be directly cooled by the fan, is 1" of air movement enough to keep the rest of the cab cooled or will I need to add a 2nd exhaust to the cab? I'm trying to keep the outlets to a minimum. It'd be a lot easier hooking up a scrubber if I can stick with one outlet. TIA

if you leave the other end of the cooltube open, its going to suck the smell up threw the light and out inn your house.go to lowes and buy a exuast fan for the top your cabinet.and run your exaust fan line to your carbon filter outside of the cabinet.and run your light exaust to the carbon filter as well,too run both of the vents to 1 carbon filter lowes sales a y thats fits on a six inch carbon filter. so both vent hoses are connecting to the y and the y is on the carbon filter. hope I helped PH2