well, theres been quite a few of these threads lately... anyway..
basicly it spins a twister, all the twister does is looks cool and sprays the water, from the water spray that drips down the side walls, water evaporates, you may put a fan blowing thru there or not, suposely in pepsi's theory air gets sucked and pushed thru there naturally
to make the twister, you need a tube, with a hole(depends on gph of the pump), a pump, and gravity, you need a side inlet or some sort of jet, then that starts the spinning then gravity does the rest,
the hole in the bottom depends on the gph of the pump, if its a high gph pump, you make the hole bigger acording to how high the twister is wanted. If its lower gph pump, you make the hole smaller to an extent
im sure youll understand now
thats aprox what mine will look like(bottom tank diff shape)