Staining is not so much a problem of changing colors, as it is more a theory of a lasting film that can retard the cooling process. I tend to side with those that think the film can reduce cooling efficiency of the loop. But it wont do so at such a level to render it useless. I guess you should decide if you are after pure 1. performance, or 2. a mix of performance and style, or 3. straight up style. If option 2 or 3 are your primary goals, and you know that you're pretty much stuck with that color, then dont worry about it and just get a quality dye. The performance knock should be small, and the extra wear on the parts is minimal at best. But if option 1 is your primary goal, then leave the dye alone, as well as a biocide. Stick with pure distilled or deionized water and silver. Wether it is coils or parts and tubing, just make sure there is enough silver in the loop. Gold also has great antimicrobial properties and is starting to be used in certain medical fields, but I've yet to see even hardcore bling-bling users drop gold in their loop. Dont really know what my thoughts on that act would be, but I know I'll see it some day.