hey dude, i have 5 plants in a space -roughly- 60cm-130cm(wide)-210 tall. i have a 400 watt hps with a growlux buld. just put a 4inch extractor fan with carbon filter in and it keeps it roughly the right temp in room, no smell at all while fan is on too which is good.
am having a little problem with my temp at times though: the other day i managed to bust the radiator in the room and now it leaks a little and i cant adjust the settings so its turned off. thing is that the pipes go through my cupboard and the rad is on wall next to it. I cant call a plummer for obvious reasons and i keep getting temps as high as 31-32c during the nights-annoying. but what can i do but open the doors once in a while? i know that doesnt sound too bad but im paranoid as the groundsman where i live is ex CID (detective) and i dont want him to see the glow from the light. hmmmm arse!