Varn V120 is not green or low VOC... There are low voc washes out there that work and work well....
You will notice that yes varn v120 and similar products pull more piment off/out of the rollers then low voc green washes, but while it is doing that, it is also leaching plastiser's out of the rollers which is a negative.
If a colour change from a dark colour to a light clean colour is needed, then the use of appropriated roller cleaner paste should be used between washes. Not relying on super strong roller washes to do it.