I have one more question fellas. I have two inline fans. One is sucking the hot air out of the hood directly outside. Now i know you say too use the other one to bring fresh air in. Well i do have a fan that is jimmy rigged from my bathroom, that is sucking fresh air from the house through a four in duct hose pulling it into my grow room/attic. (did that make sence?) So what i was hoping is that, that would be enough fresh air coming in. so that i can use the other inline fan to **** more heat out of the ventible hood. thanx for any help guys. Its about 97 degrees in there now was hoping to use the other inline fan to help pull more heat out?