the h100 would be closed loop as well. basically any liquid cooling that you buy ready to go is closed loop. on those kinds, if you open it at all, well you just ruined it since it would be very hard to seal again, if not impossible.
To get a custom uv reflective set up you'll need to build your own liquid cool from scratch. This is also far more expensive.
The best you can really do with a closed loop system is to get some UV reflective paint and paint the tubes yourself.