Question about cooling a reflector

I'm going to be upgrading my reflector to an air-cooled model. I've been looking at inline fans for the reflector and wondered how well an axial-type fan would work.
I found these... $40.00 for a 6" rated at 235 cfm. Any reason this wouldn't work with ducting?

Those will not work due to the static pressure caused by the ducting. Even the duct booster fans suck. Those are rated at 235cfm free air. Once you put on a couple of feet of duct, you are down to like 100cfm, if that. I have a crappy duct booster fan rated at 420cfm, and I hate this fan. I need a much better fan to cool my 600watt light. After the duct run, my 130cfm computer fan pushes more air than the 420cfm fan.

You want to spend the money to get a quality fan. Get a good inline fan, like a can fan. Depending on how many watts you are using will determine the CFMs needed. If you are running 400watts, a 200cfm fan should be fine, if you're running a 600-1000watts, I would suggest 400cfm.

And I forgot to mention, on ebay you can get fans like that for like $10 shipped. You can use them for intakes, just don't use them for exhaust or cooling a light.

Thank you for the information. I didn't even think about static pressure. I'll definitely look at a good inline fan.