Look man, there is a right way to do things and a wrong way. I'm not one with lots of money either but I would rather purchase a fan filter combo which you can get for less than $200 if you shop around..htgsupply.com. hint hint. I don't think its worth the risk of using a fan that is not designed for what you are wanting to use it for. Plus duct fans are specially designed for perfect airflow to get that hot air out as fast as possible while providing a good suction of air to come in. I just bought everything little by little and now my setup is as follows:

1 HPS 400 watt S51 type ballast with reflector and bulb.
1 3x3x6 hydrohut mini
1 170 cfm inline fan with elf filter scrubber
4 GH waterfarms
1 sunleaves 4 outlet air pump for lift systems
4 single air pumps for reservoir airstones
floranova grow
floranova bloom
6" clip-on fan for air movement on plants (still on the way)
1 heavy duty digital appliance timer for fan and light
SAP420 Reviewed by SAP420 on . Microwave Fan for Exhaust? We had a microwave that died a few years ago, and today I decided to experiment. I pulled out the fan, connected the two wires coming out of it to an old lamp cord, plugged it in, and voila, it works! I've been looking for a cheap exhaust fan for my grow cabinet (4'H x 2.5'W x 2'D) and I'm wondering if this just might work. The fan blade is only 4.5" across, but the whole thing must weigh close to 2 pounds. It blows like a mini-jet propeller, and from googling the CFM of microwave fans, Rating: 5