It has been decided!
We have a space constraint of 1x1x2 meters. We'll use bongs either in this arrangement (viewed from above)
..\...../
...OO
....O
.....|
Where the circles represent the bongs and the lines represent the "squirrel" cage blowers. IGNORE THE DOTS.
Yet another idea:
..OOOO
......|
Same as above, one squirrel cage blower distributed among 4 bongs. In both cases, the bongs will be glued with each other.
The pump should be functional. It is just a working model, it only has to work for the amount of time it'll be exibited
Before attaching the bong(s) to a computer, we'll first simulate the heatload and record the temperature of the water accordingly. After that, one can easily calculate the maximum number of computers that can be attached to the system. Finding a heater element is an easy task but finding a variable resistor that can handle 10 amps

at 240V is a different story.
Anyone care to enlighten us?