[Varsis]

yes you need a fan in the bottom of that setup to blow outside cool air up thru the tube . its called a bong cooler, works like the nuclear plants
its an evaporative cooling measure, the water cools as it evaporates. be prepared to use a rather good size resevoir with it, and be prepared to refill that resevoir every few days to a week depending on how efficient your bong is.
it canbring temps below ambient with a very good cooler.