UV Pink (or some call UV red) will stain like mad UV clear blue will never stain.
Red, yellow, orange, blue, green, UV yellow green, UV green, UV blue take a while to stain depending on the amount you use.
If you would like colour but don't what staining don't add to much tint (dye) to the water. Heat has a large factor in staining as well and the hotter your Loop the more it will stain. Allso take into account the PH level as this all so helps staining. Keeping it around 6.5 to 8 you should be oky with slow staining (expect for UV pink this is just horrendous for staining and cannot be avoided).
Pigments do not stain and never will. Pigments use a binder (vehicle to carry the pigment along it merry way) dyes do not. Pigments are not dyes they are crushed plastic or crushed minerals (man made or other wise stated normally via MSDS Sheets), Pigments are insoluble in liquids and Dyes are soluble. For some stupid reason "some"makers of water cooling based dyes and fluids don't even know what they put in there dyes and incorrectly name them pigments (this is a big give away they do not make there own fluids and don't even know what's in them and this is were we differ).
e.g Aurora use pigments and dyes, Pastel uses nano pigments and dyes, x1 is dye based. Cameleon (unrealised to public) is slurry, pigment, nano pigment and dye based.
We've have been working on a pigment based fluid for quite some time with the first attempts marked down as complete failures.
Mick