AndyBotwin
Weed Whisperer
Putting a 600w HID in a 6x2.5 closet is going to generate some serious heat. You'll need to get cool air in there and route the hot air out. Do you have a window nearby or can you vent to the attic? As for carbon filters, my take is that if you are serious about growing over the long term, go ahead and get one. I did the DIY route and it was OK for a small scale grow, but it's never going to do the job of a dedicated filter. Even if you are a legal grower, there's no point in possibly attracting attention you don't need. Not to mention you can get a decent entry level filter on Amazon for under $40, so it's not that expensive.