Here's another good DIY carbon filter idea. In a pinch, you could probably build it using a cardboard box instead of plywood.

http://boards.cannabis.com/indoor-gr...round-2-a.html

Most bathroom exhaust fans range from about 50 to 90 CFM. I started out with a 90 CFM fan on my tent (smaller than yours) and it didn't have enough power to pull air through the filter. I then went with a 500 CFM inline duct fan. Again, trying to save money. It will pull through the filter but still doesn't do as well as I would like. I seriously doubt it actually pulls 500 CFM. My next upgrade will be to go ahead and shell out the coin for a proper fan.

I tried the clip-on fan and wasn't happy with it. I bought a desk top size oscillating fan. That worked out much better.

Regardless of what watt CFL's you use, they need to be as close to your plants as you can get them without causing too much heat on the plant or burning the leaves. I'm using houshold CFL's and keep them about 1/2 to 1 inch from the tops of the plants. When your plants are young, keep the lights about 2 inches above the plants. Your 250's may run too hot to put that close.

For good info on ventilation, see this stickie:

http://boards.cannabis.com/indoor-gr...-progress.html

Not sure what you mean by TFL. If you meant LST, you can use the search function and find lots of instructions on the forum.

Not sure what spectrum your 250's are. I used 6700K bulbs for vegging and I have 2700K bulbs in for flower along with 2 4100K 4 foot flouros for side lights.