Check amazon, phresh makes a 4 inch. Heat or not it will still smell. I had a DIY carbon that I made, it worked but it was so loud, louder then the 6 inch vortex. I have a vortex in my tent and it's not even half as loud as I thought I was going to be. I bought a speed control for it and haven't even used it because it's not loud at all. I could hear my old one through the walls and outside the room. No ballast for cfl's, just screw them in and go. I don't know do what works best for you. I started out with cfl's in the closet and was happy with my own smoke, but depending on how into it you are you are going to want more, bigger, better, etc. It's like getting a motorcycle, hell yes a 600 is a really nice bike but after awhile your going to want the 1000 or the 1200. Looking back on it now I should have got the 8 inch instead of the 6. Everyone is different, for me more is always better. Like a 1000 dimmable ballast can go lower but a 600 watt will never be more then 600.