Yes, you need a fan to circulate the air so you have consistent temps throughout the incubator. You may only have one clutch the first time but you may have more later. You probably will only need one fan as long as the volume of air it moves is sufficient. I didn't use a computer fan but instead used a fan that was designed for use in bigger cabinets, such as large speaker boxes or larger cooling units. You can find them on Amazon and you can get them with a rheostat on the cord so you can control the speed of the fan and move as much or as little air is needed to stabilize the entire incubator.
I have the heat tape on a separate plug, plugged into the thermostat. The fan is just plugged into a power strip as I want it to remain on all the time and I do not want it to fluctuate.
I hope that helps and best of luck to you.
Can you get me the link for the page where i can buy the same fan from amazon?
where did you get the rheostat from?
Is it easy to wire it?
Sorry this is my first incubator project and i dont know nothing about electronics but im really excited to do it myself