If I didn't want feedback, I wouldn't have posted it
I've been running 100%
Koolance 702 UV-Blue in my system, and will probably continue to do so. Good to -5C and anti-corrosion/biological. UV is good for detecting leaks.
As far as the rest of the cooling system is concerned, I've left a lot of it with the facilities guys at the plants. Some of the crazier thoughts I may have encouraged involve no fans anywhere in the system:
1. giant array of radiators next to system (either truck heater cores, radiators, old cast-iron steam radiators, etc).
2. Coils of pipe buried underground below frost line (my favorite).
3. Giant reservoir with passive fins on the exterior
My main concern is to make sure that whatever pump they have in mind doesn't cause enough head pressure to pop my fittings. For that matter it will probably be two pumps in parallel with check valves for redundancy.