an inch is enough. most def
anbesol Reviewed by anbesol on . 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 Rating: 5