I am currently building my first vivarium, its coming along quite nicely. Ok so its a standard 29 gallon and I have been wondering about ventilation. My friend has obtained for me two computer cooling fans. They have moderate put out, but nothing drastic at all. In lou, what is the best way to ventilate the tank. Should I even worry about it, or If i hook the fans up, should one be blowing in and one out. Or would a small slit in the tank top be suffient for the cause. I am going to have running water in the tank to help boost humidity.