BB:

As you lower the water temp it takes more and more surface area to keep a constant rate of evaporation. This is because the water molecules are less energetic and require increasingly unfavorable transfers of energy to evaporate.

Theres no reason you can't get much lower then 3C. Here in Tucson on a 110F day, a good evap will exhaust at 75F or even less. Thats a 35F+ drop! Its just an issue of how much air flow you can aim and how much surface area the recieving water has. The units here have MASSIVE blowers (you could stick your shoulders in easily, when they're off of course :) ). Then they blow through whats basically a thick layer of thin cut woodchips that have water draining through them.

Edit: Though I imagine the ambient temps we deal with are a big concern. Its a lot easier to evaporate water at 45C then at 25C.

Personally I find having a 7ft tall tube with dual shower heads and dual pumps fine, totally sealed and efficent to cool a XP2400 to around room temps (25c~).

At first it was worse than having 8 fans running with the loud water contact at the bottom of the tube, but after placing some aquarium filter media it was nearly silent and just as cool :)

The tube i used was copper from a industrial supplier. Gave good thermal contact from the water to the outside air.

Wow, sounds nice (and heavy!)!!!
Any pic's at hand, maybe?:cool:

Ummm, ill c if i still got a webcam about, looks nice 2 cos i pollished it up :D