Yes i had some fluo tubes for a while with a different color coolant running through it. But i had to clean the pump from all the blue residue
Most additives have color as well. More for show than functional.
There is even cooling fluid that changes color, depending on temperature (Jekill and Hyde) and a lot of other stuff.
Demineralized water is even better than destilled water. And with some glycol added to it, you never have algea or mineral deposits in your loop. I bet it is even better than what is in the factory cooling solutions from coolermaster and corsair, lol
And even with non corrosive cooling fluids, you still have to be careful not to match aluminum radiators with copper cooling blocks etc. All copper is still the best, but also the most expensive.
Custom plexiglass loops like they machined for this build are awesome. But you need to know what you are doing. Getting it watertight is more difficult than it may appear. Also making all the hard tubes exactly the right length is precision work.
I think when you have build a few cases with watercooling yourself, you appreciate even more what they puilled off with this build.
Maybe my next rig will have a MB and GFX that support water loops.